Angiotensin II causes hypertension and cardiac
hypertrophy through its receptors in the kidney
Steven D. Crowley*, Susan B. Gurley*, Maria J. Herrera*, Phillip Ruiz†, Robert Griffiths*, Anil P. Kumar*,
Hyung-Suk Kim‡, Oliver Smithies‡, Thu H. Le*, and Thomas M. Coffman*§
*Department of Medicine, Duke University Medical Center and Durham Veterans Affairs Medical Center, Durham, NC 27710;†Department of Pathology,
University of Miami, Miami, FL 33136; and‡Department of Pathology, University of North Carolina, Chapel Hill, NC 27599
Edited by Richard P. Lifton, Yale University School of Medicine, New Haven, CT, and approved September 27, 2006 (received for review July 3, 2006)
Essential hypertension is a common disease, yet its pathogenesis is
not well understood. Altered control of sodium excretion in the
kidney may be a key causative feature, but this has been difficult
to test experimentally, and recent studies have challenged this
hypothesis. Based on the critical role of the renin-angiotensin
system (RAS) and the type I (AT1) angiotensin receptor in essential
hypertension, we developed an experimental model to separate
AT1 receptor pools in the kidney from those in all other tissues.
Although actions of the RAS in a variety of target organs have the
potential to promote high blood pressure and end-organ damage,
we show here that angiotensin II causes hypertension primarily
through effects on AT1receptors in the kidney. We find that renal
AT1 receptors are absolutely required for the development of
angiotensin II-dependent hypertension and cardiac hypertrophy.
When AT1receptors are eliminated from the kidney, the residual
repertoire of systemic, extrarenal AT1receptors is not sufficient to
induce hypertension or cardiac hypertrophy. Our findings demon-
strate the critical role of the kidney in the pathogenesis of hyper-
tension and its cardiovascular complications. Further, they suggest
that the major mechanism of action of RAS inhibitors in hyperten-
sion is attenuation of angiotensin II effects in the kidney.
transgenic mice ? kidney transplantation ? blood pressure
disease) are a major public health problem (1). Despite decades of
scrutiny, the precise pathogenesis of essential hypertension has
defective handling of sodium by the kidney and consequent dys-
regulation of body fluid volumes is a requisite, final common
studies of Lifton and associates showing that virtually all of the
Mendelian disorders with major impact on blood pressure ho-
meostasis are caused by genetic variants affecting salt and water
reabsorption by the distal nephron (3). On the other hand, several
recent studies have suggested that primary vascular defects may
cause hypertension by impacting peripheral resistance without
direct involvement of renal excretory functions (4–7).
Among the various regulatory systems that impact blood pres-
sure, the RAS has a key role. Inappropriate activation of the RAS,
as in renal artery stenosis, leads to profound hypertension and
cardiovascular morbidity (8). Moreover, in patients with essential
inhibitors and angiotensin receptor blockers (ARBs) effectively
(9–11), suggesting that dysregulation of the RAS contributes to
their elevated blood pressure.
At the cellular level, responsiveness to angiotensin II (Ang
II) is conferred by the expression of the two classes of
angiotensin receptors (AT1and AT2). The effects of Ang II to
increase blood pressure are mediated by AT1receptors (12),
and these receptors are expressed in a variety of organ systems
thought to play key roles in blood pressure homeostasis,
igh blood pressure (BP) is a highly prevalent disorder, and its
complications (including heart disease, stroke, and kidney
including the heart, kidney, blood vessels, adrenal glands, and
cardiovascular control centers in the brain (13). For example,
in the vascular system, stimulation of AT1 receptors causes
potent vasoconstriction (14, 15). In the adrenal cortex, their
activation stimulates the release of aldosterone (16) that in
turn promotes sodium reabsorption in the mineralocorticoid-
responsive segments of the distal nephron (17). In the brain,
intraventricular injection of Ang II causes a dramatic pressor
response that is mediated by AT1A receptors (18). In the
kidney, activation of AT1 receptors is associated with renal
vasoconstriction and antinatriuresis (19, 20). Nevertheless,
whether angiotensin actions in these individual tissue sites
contribute in vivo to the pathogenesis of hypertension and its
complications is not clear.
To address this question, we used a kidney cross-transplantation
strategy to separate the actions of AT1receptor pools in the kidney
from those in systemic tissues. Our findings suggest that AT1
receptors expressed in the kidney are the primary determinants
of hypertension and end-organ damage in Ang II-dependent
Kidney Cross-Transplantation Model. We used a kidney cross-
transplantation strategy to separate the actions of AT1receptor
pools in the kidney from those in systemic tissues, as we have
described previously (21). Kidney transplantation was carried out
between genetically matched F1(C57BL?6 ? 129) wild-type mice
and F1(C57BL?6 ? 129) mice homozygous for a targeted disrup-
tion of the Agtr1a gene locus encoding the AT1Areceptor (14). The
AT1Areceptor is the major AT1receptor isoform in the mouse and
generated four groups of animals in which renal function was
provided entirely by the single transplanted kidney. The Wild-type
group consisted of wild-type mice transplanted with kidneys from
wild-type donors and thus have normal expression of AT1Arecep-
tors in the kidney transplant and in all systemic tissues. For the
Systemic KO group, AT1Areceptor-deficient recipients were trans-
planted with kidneys from wild-type donors; these animals lack
AT1Areceptors in all tissues except the kidney. Kidney KO animals
are wild-type recipients of AT1Areceptor-deficient kidneys, thus
lacking expression of AT1Areceptors only in the kidney, but with
normal expression of receptors in all systemic, nonrenal tissues,
including the adrenal gland. Finally, the Total KO group consists of
AT1Areceptor-deficient recipients of AT1Areceptor-deficient kid-
neys and therefore completely lacking AT1Areceptors in all tissues.
Author contributions: S.D.C., O.S., T.H.L., and T.M.C. designed research; S.D.C., S.B.G.,
M.J.H., P.R., R.G., A.P.K., and H.-S.K. performed research; S.D.C., S.B.G., P.R., T.H.L., and
T.M.C. analyzed data; and S.D.C., O.S., T.H.L., and T.M.C. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS direct submission.
§To whom correspondence should be addressed at: Duke University Medical Center,
Box 3014, Durham, NC 27710. E-mail: email@example.com.
© 2006 by The National Academy of Sciences of the USA
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Baseline Blood Pressure Measurements. One week after the trans-
plantation procedure, radiotelemetry transmitters were implanted
to provide direct measurements of arterial pressures in the mice in
a conscious and unrestrained state. One week after placement of
of blood pressure, blood pressure measurement was initiated.
Baseline blood pressures in the Systemic KO and Kidney KO groups
were virtually identical [109 ? 1 mmHg vs. 109 ? 1 mmHg (1
mmHg ? 133 Pa)] and intermediate to those of the Wild-type
(114 ? 2 mmHg) and Total KO (97 ? 2 mmHg) groups, consistent
AT1receptors make equivalent contributions to the level of blood
pressure in the basal state.
A Major Role for AT1 Receptors in the Kidney in Ang II-Dependent
Hypertension. To distinguish the AT1receptor population that is
critical for the pathogenesis of hypertension, osmotic minipumps
were implanted s.c. into each animal to infuse Ang II (1,000
ng?kg?min) continuously for 4 weeks. This is a widely used model
of experimental hypertension in which elevated blood pressure is
mediated by ligand stimulation of AT1receptors causing significant
end-organ damage, including cardiac hypertrophy (22–24). Upon
initiation of Ang II infusion, mean arterial pressures (MAP) in the
Wild-type transplant group rose dramatically to almost 160 mmHg
(Fig. 1A) and remained elevated throughout the infusion period
of ? 55 ? 3 mmHg). This degree of blood pressure increase is
similar to that seen in previous studies using nontransplanted mice
(23), suggesting that the transplant procedure and the presence of
only a single kidney does not significantly alter blood pressure
responses to chronic Ang II infusion. By contrast, blood pressures
in the Total KO animals that are completely devoid of AT1A
reflecting the key role of AT1 receptors in the development of
hypertension in this model (MAP of 104 ? 3 mmHg at Week 3).
The modest (? 6 ? 3 mmHg; P ? 0.05) increase in blood pressure
receptor isoform, AT1B, which is unaffected by the AT1A gene
The Kidney KO animals (Fig. 1A) experienced an immediate
increase in blood pressure when the Ang II infusion was initiated,
peaking on Day 2 (135 ? 5 mmHg; P ? 0.0003 vs. Kidney KO
baseline) and rapidly receding thereafter. However, at every time
point, including Day 2, blood pressures in the Kidney KOs were
significantly lower than those in the Wild-type group. Accordingly,
the degree of hypertension was markedly attenuated in the Kidney
pressure increase in the Kidney KO group was not different from
that seen in the Total KOs (? 15 ? 4 mmHg; P ? NS vs. Total KO).
Despite the early and transient increase in blood pressure, presum-
ably due to peripheral vasoconstriction, the absence of AT1A
receptors in the kidney alone is sufficient to protect from Ang
In contrast, in the Systemic KO animals expressing AT1Arecep-
tors only in the kidney (Fig. 1A), MAP rose progressively over the
first 2 weeks of Ang II infusion. Yet, their blood pressures lagged
behind the higher pressures seen in the Wild-type group for the first
10 days, likely reflecting the transient contribution of the early
Day 4 onward, blood pressures in Systemic KOs significantly ex-
ceeded those of the Kidney KOs (P ? 0.008). Furthermore, by Day
12, blood pressures in the Systemic KOs converged with and were
virtually identical to those of the Wild-type group (161 ? 5 mmHg
for Week 3; mean BP increase of ? 51 ? 4 mmHg; P ? NS vs.
Wild-type; P ? 0.0003 vs. Kidney KO). Accordingly, the presence of
AT1Areceptors in the kidney alone is sufficient to recapitulate the
hypertension phenotype of the Wild-type group. Together, these
data show that Ang II causes hypertension primarily through AT1A
receptors expressed in the kidney.
Urinary Sodium Excretion. We reasoned that activation of AT1
receptors in the kidney might cause hypertension by influencing
excretion between the experimental groups during the first week of
Ang II infusion. The animals were placed in metabolic cages (25),
and food and water intakes were matched to avoid confounding
effects of variable intake on urinary electrolyte excretion. Before
implantation of Ang II-infusion pumps, total urinary sodium ex-
cretion (UNaV) was similar in the four experimental groups (not
shown). In contrast, cumulative sodium excretion measured during
in the hypertensive Wild-type and Systemic KO groups compared
AT1Areceptors in the kidney and are resistant to the hypertensive
actions of Ang II (Fig. 1A).
Impaired sodium excretion by the kidney may increase blood
pressure by expanding intravascular fluid volume (2), which should
be reflected acutely by changes in body weight. Therefore, to
determine whether the reduced sodium excretion in the Wild-type
and Systemic KO groups led to volume expansion, we compared
cross-transplantation. (A) Daily, 24-h blood pressures in the experimental
groups before (‘‘pre’’) and during 21 days of Ang II infusion (*, P ? 0.03 vs.
Wild-type; §, P ? 0.008 vs. Systemic KO; †, P ? 0.006–0.0001 vs. Wild-type). (B)
Cumulative sodium excretion during the first 5 days of Ang II infusion. (§, P ?
KO). (C) Change in body weights after 5 days of Ang II infusion. (*, P ? 0.03 vs.
‘‘pre’’; #, P ? 0.05 vs. ‘‘pre’’).
Blood pressures and urinary sodium excretion in mice after kidney
www.pnas.org?cgi?doi?10.1073?pnas.0605545103Crowley et al.
body weights at baseline and after 5 days of Ang II infusion. Body
weights increased significantly in the Wild-type (? 5.9%) and
Kidney KO and Total KO groups (Fig. 1C), exactly paralleling the
II causes hypertension by activating AT1receptors in the kidney
promoting sodium reabsorption. Conversely, when AT1receptors
in the kidney are absent, sufficient sodium is excreted in the urine
to protect against the development of hypertension. These findings
suggest that ACE inhibitors and ARBs reduce blood pressure in
hypertensive patients by attenuating AT1receptor signals in the
kidney, thereby facilitating excretion of sodium.
Cardiac Hypertrophy Depends on Blood Pressure Elevation Rather
Than Expression of AT1 Receptors in the Heart. In patients with
hypertension, one of the early and most common consequences of
presence of LVH is associated with significant cardiovascular risk
(26, 27). Clinical evidence suggests that the RAS contributes to the
development of LVH in hypertension (28–30). In our experiments,
Systemic KO animals develop severe hypertension but lack AT1A
receptors in the heart. Conversely, Kidney KO animals are resistant
to Ang II-induced hypertension but have a full complement of
cardiac AT1Areceptors. Thus, we reasoned that we could use our
cellular actions of AT1receptors in the development of cardiac
Accordingly, we compared heart size in the four experimental
cardiac hypertrophy (Fig. 2 A, E, and I), the extent of which was
similar to that of previous studies with intact Wild-type animals
infused with Ang II (23). In the Systemic KO group, which develop
hypertension but lack AT1Areceptors in the heart, the degree of
cardiac hypertrophy and increased left ventricular wall thickness
was similar to that in the Wild-type group (Fig. 2 B, F, and I),
indicating that cardiac AT1 receptors are not necessary for the
KO group, with the normal complement of cardiac AT1Areceptors
but without hypertension, there was no evidence of hypertrophy
after Ang II infusion (Fig. 2 C, G, and I). Moreover, heart sizes and
weights in the Kidney KO group were virtually identical to those of
the Total KO group (Fig. 2 D, H, and I). These results suggest that
prolonged stimulation of AT1receptors in the heart, without blood
pressure elevation, is not sufficient to cause cardiac hypertrophy in
tive hearts and left ventricular cross-sections after 28 days of Ang II infusion:
A and E, Wild-type; B and F, Systemic KO; C and G, Kidney KO; D and H, Total
KO. (I) Mean heart-to-body weight ratios after 28 days of Ang II infusion. The
dashed line represents the mean heart-to-body weight ratio for noninfused
Wild-type mice established in previous experiments in our laboratory (23).
Wild-type and Systemic KO groups exhibit significant cardiac hypertrophy.
blood pressure (R ? 0.84. P ? 0.0001).
Cardiac hypertrophy with angiotensin II infusion. (A–H) Representa-
photomicrographs of heart sections stained with Masson trichrome. (Magni-
and myocyte injury were common in hearts from the Wild-type (A) and
Systemic KO (B) groups, whereas myocardial and vascular morphology were
normal in the Kidney KO (C) and Total KO (D) groups. (E) Semiquantitative
scoring of cardiac pathology (§, P ? 0.002 vs. Kidney KO and P ? 0.0003 vs.
Total KO; ‡, P ? 0.02 vs. Kidney KO and P ? 0.004 vs. Total KO).
Cardiac injury after angiotensin II infusion. (A–D) Representative
Crowley et al.
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weight and blood pressure across all four experimental groups,
suggesting that cardiac hypertrophy depends primarily on the level
of blood pressure rather than the presence of AT1receptors in the
Cardiac Pathology with Ang II Hypertension. We next examined the
extent of cardiac histopathology in the four experimental groups.
Sections from the Wild-type and Systemic KO groups showed
significant and similar degrees of pathology (Fig. 3 A and B),
myocardial injury. In contrast, vessel wall structure and myocardial
architecture were normal in the Kidney KO sections (Fig. 3C) and
quantitative scoring (Fig. 3E), the two groups with hypertension
(Wild-type and Systemic KO) displayed significant cardiac injury
cardiac injury was minimal in the Kidney KO group despite their
normal expression of cardiac AT1Areceptors.
Cardiac Gene Expression Patterns During Ang II Hypertension. Al-
though our evaluations of heart weight and histology indicate a
dominant effect of blood pressure on cardiac pathology, we con-
sidered the possibility that these assessments might not be suffi-
myocytes. During hypertrophic cardiac remodeling, gene expres-
sion in myocardium undergoes characteristic alterations, including
enhanced expression of atrial natriuretic peptide (ANP) and brain
natriuretic peptide (BNP), along with recapitulation of fetal gene
expression patterns for myosin heavy chains (MHC) characterized
by a down-regulation of ?-MHC and up-regulation of the ?-MHC
isoform (31–34). Previous studies have suggested that Ang II may
stimulate these processes (35, 36). We therefore examined cardiac
mRNA expression for ANP, BNP, ?-MHC, and ?-MHC after 4
weeks of Ang II infusion. As shown in Fig. 4A, levels of mRNA for
both ANP and BNP were both dramatically increased in hearts
from Wild-type animals compared with hearts from the Total KO
despite their lack of cardiac AT1A receptors. In contrast, up-
regulation of ANP or BNP mRNAs was not detected in the Kidney
A similar pattern was observed in our measurements of ?-MHC
and ?-MHC mRNA levels. As depicted in Fig. 4B, the ratio of
?-MHC??-MHC expression was increased by nearly 4-fold in the
Wild-type and Systemic KO groups compared with the Kidney KO
and Total KO groups.
A major role for the RAS in promoting hypertension and its
associated end-organ damage has long been recognized (37–39).
These actions are mediated primarily by AT1receptors (30, 40).
Expression of AT1receptors in key sites involved in regulation of
peripheral vascular resistance, sodium balance, and activity of the
blood pressure homeostasis. Because pharmacological antagonists
and conventional gene knockouts produce global inhibition of AT1
receptors, it has been difficult to discriminate clearly which of these
of kidney cross-transplantation in the mouse that allows for sepa-
ration of AT1receptor pools in the kidney from those in other
A major finding in our study is that AT1receptors in the kidney
are primarily responsible for the actions of Ang II to cause
hypertension. This is clearly illustrated in the Systemic KO animals,
to recapitulate the phenotyope of hypertension with Ang II infu-
sion. Conversely, in the Kidney KO group, the absence of AT1
receptors from the kidney alone is sufficient to protect these
animals from Ang II-dependent hypertension, despite the expres-
sion of AT1A receptors in a number of other key areas that
potentially impact blood pressure homeostasis, including the brain,
the heart, the peripheral vasculature, and the adrenal gland. The
mechanism for the distinct blood pressure responses in the two
groups appears to be related to differences in renal sodium han-
dling. Ang II infusion is associated with reduced renal sodium
excretion and weight gain in the Systemic KO group, whereas the
enhanced natriuresis, no change in weight, and resistance to hy-
pertension. It is important that these effects on blood pressure and
within the kidney, independent of any contribution of Ang II-
dependent aldosterone release.
throughout the nephron, in the glomerulus, and on the renal
sodium reabsorption by coordinately stimulating the sodium-
potassium ATPase on the basolateral surface (43, 44). AT1recep-
tors also affect sodium reabsorption in distal nephron segments,
(45–48). In the collecting duct, for example, Bell and associates
have shown that Ang II directly stimulates epithelial sodium
channel activity through an AT1receptor-dependent mechanism
(49). AT1receptors expressed in the renal vasculature also have
important regulatory effects on sodium handling (50). Renal va-
soconstriction caused by Ang II, which we have previously shown
53). Our study suggests that the primary mechanism of action of
patients is attenuation of AT1receptor signals at one or more of
these key sites in the kidney.
we found that AT1receptor actions in the kidney and extrarenal
Expression of ANP and BNP mRNA in hearts (n ? 8 per group; §, P ? 0.003 vs.
vs. Total KO;*, P ? 0.02 vs. Kidney KO and P ? 0.002 vs. Total KO; #, P ? 0.01
vs. Kidney KO and P ? 0.002 vs. Total KO). (B) Ratio of cardiac ?-MHC-to-?-
MHC mRNA expression in hearts. (§, P ? 0.01 vs. Kidney KO and P ? 0.03 vs.
Total KO; ‡, P ? 0.002 vs. Kidney KO and P ? 0.01 vs. Total KO).
Cardiac gene expression in mice infused with angiotensin II. (A)
www.pnas.org?cgi?doi?10.1073?pnas.0605545103 Crowley et al.
tissues made virtually equivalent contributions to preventing hypo-
tension and supporting normal blood pressure (21). Thus, when
circulatory volumes are threatened, the full range of AT1receptor
actions at key tissue sites is activated and apparently necessary to
protect against circulatory collapse. On the other hand, their
relative contributions appear to be quite different in hypertension
where the population of AT1receptors in the kidney assumes a
preeminent role. In this regard, Guyton hypothesized that the
substantial capacity for sodium excretion by the kidney provides a
compensatory system of virtually infinite gain to oppose processes,
including increases in peripheral vascular resistance, which would
tend to increase blood pressure (2). It follows that defects in renal
a chronic increase in intra-arterial pressure. Our current findings
confirm the key role of altered renal sodium handling in Ang
II-dependent hypertension and are completely consistent with
There was a statistically significant increase in blood pressure in
the Kidney KO group coinciding with the initiation of the angio-
Day 2 and then gradually returned toward baseline. We speculate
that this early change in blood pressure was due to vasoconstriction
mediated by AT1receptors in the peripheral vasculature. Its rapid
attenuation was likely due to the accompanying natriuresis. This
pattern illustrates the relatively modest contribution of systemic
vasoconstriction, in isolation, to the development of Ang II-
dependent hypertension. Even at their peak, blood pressures in the
Thus, chronic systemic vasoconstriction driven by Ang II has a very
limited capacity to cause sustained hypertension.
The pattern in the Systemic KO group was quite different. Blood
pressure increased progressively during the first 2 weeks, although
the rate of rise was delayed compared with that of the Wild-type
group. We suggest that this early difference reflects the absence of
time, however, pressures in the Systemic KOs eventually reach the
level of the Wild-type group, indicating that AT1receptor actions in
the kidney are sufficient to generate the full hypertension pheno-
type. Moreover, as discussed below, the similar extent of cardiac
hypertrophy seen in the Wild-type and Systemic KO groups, and its
complete absence in the Kidney KO group, suggests that the late,
sustained phase of hypertension provides the major stimulus for
end-organ injury in this model.
A major goal of hypertension treatment is to prevent or ame-
liorate injury to key target organs, including the heart, kidney, and
brain. One of the most prevalent manifestations of end-organ
damage in hypertension is the development of LVH (26), and its
presence confers substantial cardiovascular risk (26, 27). Although
pressure load from elevated blood pressure clearly contributes to
LVH, several lines of evidence suggest that activation of the RAS
stimulates hypertrophy of cardiac myocytes in culture (54, 55). In
addition, clinical studies have demonstrated actions of ACE inhib-
itors and ARBs to cause regression of LVH more effectively than
other classes of antihypertensive agents with similar levels of blood
pressure control (28–30).
Although distinguishing the relative contributions of hyperten-
sion and cardiac AT1receptor activation to the development of
LVH in vivo has been difficult, we reasoned that our model might
be useful for this purpose. The extent of blood pressure elevation
was very similar in the Wild-type and Systemic KO groups, but they
differ in their expression of AT1Areceptors in the heart. Despite
lacking cardiac AT1Areceptors, the Systemic KO group developed
robust LVH with heart weights that were not significantly different
from those of the Wild-type group. By contrast, Kidney KOs with a
normal complement of cardiac AT1A receptors do not develop
the presence or absence cardiac AT1Areceptors. Thus, in a simple
model of Ang II-dependent hypertension, the severity of cardiac
hypertrophy was exclusively dependent on blood pressure. We
found no evidence for a contribution of direct actions of AT1
receptors in the heart to promote LVH. Although our data are
prospective clinical trials demonstrating beneficial effects of ACE
inhibitors or ARBs on regression of LVH (29, 30). Rather, they
suggest that the benefits of these agents in LVH are not a conse-
quence of blocking cellular actions of Ang II in the heart, but may
be due to differences in the degree or pattern of blood pressure
control that was achieved (56).
Direct effects of AT1receptor activation to promote inflamma-
tion, fibrosis, and vascular damage have been implicated as path-
ways for facilitating end-organ damage in hypertension (22, 24,
fibrosis and vascular pathology in the Wild-type and Systemic KO
groups. On the other hand, hearts in the Kidney KOs appeared
virtually normal, indicating that vascular injury and fibrosis in the
heart were also consequences of elevated blood pressure rather
than local actions of cardiac AT1receptors. Cardiac hypertrophy is
ing up-regulation of ANP and BNP (31, 32), and recapitulation of
fetal patterns for expression of myosin heavy chains (33, 34). It has
been suggested that activation of AT1receptors in cardiomyocytes
may be sufficient to trigger this transcription profile (34, 35).
However, as we observed with cardiac hypertrophy and pathology,
activation of AT1 receptors in the heart is not responsible for
characteristic gene expression patterns associated with Ang II
infusion; these are also triggered by elevated blood pressure.
expressed in the kidney that reduce urinary sodium excretion. This
or require angiotensin II-mediated aldosterone responses in the
adrenal gland. Our findings suggest that the mechanism of antihy-
pertensive actions of ACE inhibitors and ARBs involves attenua-
tion of the renal actions of angiotensin II. Furthermore, these
experiments indicate that the major mechanism of protection from
cardiac hypertrophy afforded by these agents is related to blood
pressure control rather than inhibition of AT1receptor actions in
Materials and Methods
Animals. (129 ? C57BL?6)F1mice lacking AT1Areceptors for Ang
II were generated as described in ref. 14. Animals were bred and
maintained in the animal facility of the Durham Veterans Affairs
Medical Center under National Institutes of Health guidelines.
These studies used 2- to 4-month-old male mice.
Mouse Kidney Transplantation. Vascularized kidney transplants
were performed in mice as described in ref. 21. The donor kidney,
ureter, and bladder were harvested en bloc, including the renal
artery with a small aortic cuff and the renal vein with a small vena
caval cuff. These vascular cuffs were anastomosed to the recipient
abdominal aorta and vena cava, respectively, below the level of the
native renal vessels. Donor and recipient bladders were attached
dome to dome. The right native kidney was removed at the time of
transplant, and the left native kidney was removed through a flank
incision 1–3 days later. The adrenal glands and their blood supply
were preserved intact. Each group consisted of at least seven
Telemetry Probe Implantation Procedure. The components of the
radiotelemetry system (Transoma Medical, St. Paul, MN), includ-
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