Baroreflex sensitivity in rabbits during the development of experimental renal hypertension and medial sclerosis.
Baroreflex sensitivity was assessed in 9 normotensive (N), 8 renal wrap (one kidney model, RH) and 16 medial sclerotic rabbits (MS, fed on calciferol 50,000 i.u. and calcium lactate 1g for 10 days) before (mean BP;N, 79 +/- 3.3 mm Hg; RH, 80 +/- 7.4 mm Hg; and MS, 83 +/- 1.0 mm Hg) and at monthly intervals for up to 16 weeks after the induction of the disease processes (mean BP;N, 87 +/- 3.9 mm Hg; RH, 127 +/- 7.2 mm Hg and MS, 99 +/- 3.8 mm Hg). Blood pressure was elevated by i.v. phenylephrine (5 and 10 micrograms.kg-1) or angiotensin (250 ng.kg-1) and baroreflex sensitivity assessed by the increase of pulse interval per unit rise of pressure. The pressor response was greater in the RH and MS than in the N rabbits. The baroreflex sensitivity showed a progressive reduction with time and with the elevation of blood pressure in both MS and RH rabbits. The difference was significantly greater (P < 0.01) than in the aged related control rabbits (P < 0.05). There was an inverse relationship between baroreflex sensitivity and the pressor response in MS rabbits. Results indicated progressive baroreceptors dysfunction in hypertensive and medial sclerotic rabbits.
D000804:Angiotensin II / Q000008:administration & dosage; D000818:Animals; D001013:Aorta, Thoracic / Q000503:physiopathology; D001018:Aortic Diseases / Q000503:physiopathology*; D001161:Arteriosclerosis / Q000503:physiopathology*; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006977:Hypertension, Renal / Q000503:physiopathology*; D007275:Injections, Intravenous; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology*; D010656:Phenylephrine / Q000008:administration & dosage; D011311:Pressoreceptors / Q000503:physiopathology*; D011674:Pulse / Q000187:drug effects; D011817:Rabbits; D012018:Reflex / Q000502:physiology*; D013997:Time Factors
D000804:Angiotensin II; D010656:Phenylephrine