[Show abstract][Hide abstract] ABSTRACT: Aging and hypertension increase the risk of erectile dysfunction (ED) and cardiovascular disease. Arterial insufficiency is likely a primary factor in hypertension-related ED. Given the dominance of internal pudendal arteries in controlling penile vascular resistance, pathological changes in this vessel would be critical for inducing ED in aged hypertensives.
We assessed the age-related impact of hypertension and its treatment on erectile function and pudendal artery structure in young and old spontaneously hypertensive rats (SHRs).
Erectile responses were monitored in 15- and 77-week-old SHR and Wistar Kyoto (WKY) rats using apomorphine (80 mg/kg). At sacrifice, the vasculature was perfusion-fixed and aorta, renal, mesenteric, and internal pudendal arteries assessed morphometrically using light and electron microscopy. A separate group of 15-week SHR were treated with enalapril and hydrochlorothiazide (30 mg/kg/day, 2 weeks) followed by 2 weeks off treatment, after which the same vessels were assessed morphometrically. Arterial pressures were determined using radiotelemetry.
Erectile function, vessel morphology (lumen diameter, wall thickness, cross-sectional area, extracellular matrix [ECM]) and arterial pressure.
Erectile responses were similar in young SHR and WKY (1.7 ± 0.80 vs. 1.4 ± 0.85) but declined significantly in aged SHR (0.3 ± 0.49). Vascular aging in SHR was associated with striking pudendal remodeling, characterized by marked neointimal proliferation and disruptions of the internal elastic lamina. This remodeling involved thickening of the medial layer (35 ± 6.0 µm vs. 81 ± 3.5 µm, P < 0.01), decreased lumen diameter (282 ± 6.3 µm vs. 250 ± 12.4 µm, P < 0.05) and increased ECM (10 ± 2.0 µm² vs. 26 ± 10.6 µm², P < 0.001). In old pudendals, there were significantly more round synthetic smooth muscle cells bordering the intima and in the neointima. Antihypertensive treatment decreased the wall:lumen ratio in young SHR pudendal arteries (-17%).
Vascular aging in SHR with ED involved distinctive pathogenic remodeling in the internal pudendal artery. In young SHR, brief antihypertensive therapy was able to regress this abnormal morphology.
Full-text · Article · Feb 2011 · Journal of Sexual Medicine
[Show abstract][Hide abstract] ABSTRACT: Aging increases the risk of both erectile dysfunction (ED) and cardiovascular disease. These conditions have similar etiologies and commonly coexist. One unifying concept is the role of arterial insufficiency which is a primary factor in the onset of age-related ED.
Based on the novel finding that the pudendal arteries contribute 70% of the total penile vascular resistance, our objective was to morphometrically and functionally characterize this vessel in young and old normotensive rats.
Erectile function was monitored in 15- and 77-week Sprague-Dawley rats using the apomorphine bioassay (80mg/kg, s.c.). Anesthetized animals were perfusion-fixed, aortic, renal, and internal pudendal arteries were excised, embedded, sectioned, stained, and morphometrically assessed using light microscopy. Hearts were excised, separated, and weighed prior to perfusion. Contractile and relaxation responses to acetylcholine (ACh) and phenylephrine (PE) were assessed by wire myograph.
Erectile function, morphological measurements, concentration response curves to ACh and PE.
With age, there were marked decreases in erectile responses compared to younger rats (2.8±0.87 vs. 0.3±0.58). The pudendal arteries had a relatively small lumen (303±13.8µm) and a thick medial layer (47±2.2µm). In aged pudendal arteries, the lumen diameter did not change, and yet the medial layer, cross sectional area, and extracellular matrix were markedly increased. In contrast, the lumen diameter and wall thickness of the aorta and renal arteries in aged rats increased proportionally. An increase in small, round, smooth muscle cells was seen in aged pudendal arteries. Functionally, there were no differences in contractile responses to PE; however, ACh-induced relaxation decreased with age.
In aged rats, erectile function was severely diminished when pudendal arteries had undergone marked phenotypic changes. Specifically, there was endothelial dysfunction and pathological remodeling of this vessel with age, characterized by medial thickening, impaired vasodilation and significantly reduced capacity for penile blood flow.
Full-text · Article · Oct 2010 · Journal of Sexual Medicine