Ethnic differences in resistance artery contractility of normotensive pregnant women

Depts. of Internal and Vascular Medicine, F4-222, Academic Medical Center, Meibergdreef 9, Amsterdam 1105 AZ, The Netherlands.
AJP Heart and Circulatory Physiology (Impact Factor: 3.84). 08/2010; 299(2):H431-6. DOI: 10.1152/ajpheart.00919.2009
Source: PubMed


Black women are at a greater risk to develop hypertension during pregnancy, with a 4.5 times higher rate of fatal preeclampsia than white women. Therefore, it is important to identify factors that may affect this risk. Our group previously proposed that high activity of the central regulatory enzyme of energy metabolism, creatine kinase (CK), may increase ATP-buffering capacity and lead to enhanced vascular contractility and reduced nitric oxide bioavailability. Therefore, we assessed microvascular contractility characteristics in isolated resistance arteries from self-defined black and white normotensive pregnant women using a Mulvany-Halpern myograph. Additionally, morphology was assessed with electron microscopy. Resistance-sized arteries obtained from omentum donated during cesarean sections (11 black women and 20 white women, mean age: 34 yr) studied in series showed similar morphology but significantly greater maximum contractions to norepinephrine (10(-5) M) in blacks [14.0 mN (1.8 SE)] compared with whites [8.9 mN (1.4 SE), P = 0.02]. Furthermore, we found greater residual contractility after the specific CK inhibitor dinitrofluorobenzene (10(-6) M) in black women [55% (6 SE)] compared with white women [28% (4 SE), P = 0.001] and attenuated vasodilation after bradykinin (10(-7) M) in black women [103% (6 SE)] compared with white women [84% (5 SE), P = 0.023], whereas responses to sodium nitroprusside (10(-4) M) and amlodipine (10(-6) M) were similar. We conclude that compared with white women, normotensive pregnant black women display greater resistance artery contractility and evidence of higher vascular CK activity with attenuated nitric oxide synthesis. These findings in normotensives may imply that the black population is at risk for a further incline in pregnancy-related hypertensive disorders.

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    • "In addition, the high creatine synthesis associated with the high creatine kinase activity found in persons of African ancestry [11,12,72,73], is thought to hamper the bioavailability of the precursor L-arginine shared with nitric oxide synthase (Figure 2). Thus, high CK has been shown to be associated with low vascular NO bioavailability in vitro[72], and L-Arginine was found to be low in persons of African ancestry [69], with supplementation restoring NO bioavailability in vivo[81]. However, there are no clinical data yet that associate the response of ACE inhibitors to high CK or low NO. "
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