title: Regulation of renovascular adenosine 3',5'-cyclic monophosphate in spontaneously hypertensive rats.
abstract: This study tested the hypothesis that regulation of 3',5'-cAMP levels in the kidney vasculature is abnormal in spontaneously hypertensive rats. In isolated, perfused kidneys from adult rats (16 weeks of age), isoproterenol similarly increased renal venous 3',5'-cAMP secretion from kidneys of hypertensive versus normotensive Wistar-Kyoto rats. However, a broad-spectrum phosphodiesterase inhibitor (isobutyl-1-methylxanthine) augmented isoproterenol (3 mumol/L)-induced increases in renal venous 3',5'-cAMP secretion more so in kidneys from adult hypertensive versus age-matched normotensive rats (31-fold and 5-fold, respectively; P<0.0001). In contrast to isoproterenol, broad-spectrum phosphodiesterase inhibition augmented forskolin-induced increases in renal venous 3',5'-cAMP secretion similarly in kidneys from adult hypertensive versus age-matched normotensive rats. In kidneys from adults of both strains, the effects of isobutyl-1-methylxanthine on isoproterenol-induced 3',5'-cAMP responses were mimicked by the inhibition of phosphodiesterase 4 (RO 20-1724) but not by the inhibition of phosphodiesterase 1 (3,8-methoxymethyl-3-isobutyl-1-methylxanthine) or phosphodiesterase 3 (milrinone). In kidneys from young (5 weeks of age), adult, and old (39 weeks of age) rats, RO 20-1724 augmented isoproterenol-induced renal 3',5'-cAMP secretion more so in kidneys from hypertensive rats. In adult hypertensive rats, arterial blood pressure and renal vascular resistance were elevated compared with age-matched normotensive rats, and intravenous infusions of RO 20-1724 reduced blood pressure and renal vascular resistance in hypertensive rats but had little effect on these variables in normotensive rats. We conclude that, in the renal vasculature of spontaneously hypertensive rats (young, adult, and old), there is increased activity of a compartment of phosphodiesterase 4. Selective inhibition of renal vascular phosphodiesterase 4 may represent a new strategy for improving renal hemodynamics in genetic hypertension.
authors.affiliation: Center for Clinical Pharmacology, University of Pittsburgh School of Medicine, 100 Technology Dr, Suite 450, Pittsburgh, PA 15219, USA. edj@pitt.edu
authors.forename: Edwin K
authors.initials: EK
authors.lastname: Jackson
authors.forename: Zaichuan
authors.initials: Z
authors.lastname: Mi
mesh_terms: D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001795:Blood Pressure Determination; D005576:Colforsin / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism*; D004195:Disease Models, Animal; D006978:Hypertension, Renovascular / Q000188:drug therapy / Q000503:physiopathology*; D007545:Isoproterenol / Q000494:pharmacology*; D007668:Kidney / Q000098:blood supply / Q000187:drug effects / Q000503:physiopathology; D008297:Male; D011336:Probability; D011897:Random Allocation; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012016:Reference Values; D012079:Renal Circulation / Q000187:drug effects* / Q000502:physiology; D012680:Sensitivity and Specificity; D014970:Xanthines / Q000494:pharmacology
chemical_list: C119531:8-methoxymethyl-3-isobutyl-1-methylxanthine; D014970:Xanthines; D005576:Colforsin; D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone; D000242:Cyclic AMP; D007545:Isoproterenol