Impact of antihypertensive treatments on erectile responses in aging spontaneously hypertensive rats

Objective: We previously demonstrated that brief, aggressive antihypertensive therapy recovered erectile function in 40-week-old spontaneously hypertensive rats (SHR). The present study examined the impact of antihypertensive and testosterone treatments on erectile function in aging SHR. Design and methods: Centrally initiated erections were determined in response to apomorphine throughout. At 30 and 49 weeks, SHR were treated for 2 weeks with enalapril or hydralazine. A third more aggressive treatment (68 weeks) involved enalapril or losartan plus a low salt diet or a triple therapy (hydralazine, nifedipine, hydrochlorothiazide). In a separate study, cross-over kidney transplantations were performed between untreated and losartan-treated SHR. Arterial pressure was assessed posttransplantation using radio-telemetric transducers. Results: There was an age-related decrease in erections between 30 and 68 weeks (3.1 ± 0.79 versus 0.2 ± 0.38) that was not improved by testosterone administration. Early treatment with enalapril or hydralazine did not prevent this decline, although the second treatment resulted in significant improvements (enalapril, 0.8 ± 0.70; hydralazine, 0.8 ± 0.41 versus control, 0.3 ± 0.60). A 2-week aggressive antihypertensive treatment at 68 weeks increased erections approximately two-fold, with the previously treated rats receiving triple therapy having markedly improved erectile responses (0.2 ± 0.53 versus 1.1 ± 1.67). In the transplantation study, previously losartan-treated SHR given an untreated kidney had higher arterial pressure but twice the number of erections in comparison with the SHR with lower arterial pressure resulting from transplanting a treated kidney. Conclusions: Aggressive antihypertensive treatments may be more beneficial in improving erectile function in aged SHR, via an effect that appears to be tissue specific, and not based on changes in blood pressure.