PERINDOPRIL CHANGES THE MESENTERIC PRESSURE PROFILE OF CONSCIOUS HYPERTENSIVE AND NORMOTENSIVE RATS

Information about how antihypertensive therapy affects the arterial bl ood pressure profile in conscious animals is at present not available. Here we report measurements of part of the pressure profile in consci ous spontaneously hypertensive rats (SHR, n=7) and Wistar-Kyoto (WKY, n=7) rats before and after treatment with the angiotensin-converting e nzyme inhibitor perindopril. The previously developed technique that w e used, provided simultaneous measurements of the undisturbed arterial blood pressure at the base of mesenteric arcades (P-arc; diameter, ap proximately 100 mu m) and systemic mean blood pressure (MBP). The rati o P-arc/MBP was 631+/-2% (mean+/-SEM) in SHR and 64+/-3% in WKY rats. When a bolus of perindopril (0.8 mg/kg) was injected into the aorta, P -arc/MBP fell within 2 minutes to 51+/-2% (P<.05) for SHR and 56+/-2% (P<.05) for WKY rats, and these levels were maintained for the next ho ur. In contrast, MBP did not change for approximately 5 minutes in eit her strain, whereas after 1 hour MBP still had not changed significant ly in WKY rats, but MBP had fallen by 16+/-2% (P<.05) in SHR. The expe riments suggest that in the mesentery (1) the elevated resistance in t he arterial system in SHR is present in both macroarteries tie, vessel s proximal to the base of the arcades) and in the more distal microart eries and veins, (2) for at least 1 hour perindopril caused greater di lation of the microarteries than the macroarteries, and (3) these prof ound changes in the mesenteric blood pressure profile appear to occur independently of the fall in MBP, indicating that they are not directl y associated with the blood pressure drop.