Altered protein kinase C regulation of phosphoinositide-coupled receptors in deoxycorticosterone acetate-salt hypertensive rats.
This study examined the contribution of phosphatidylinositol metabolism and the efficacy of protein kinase C-mediated desensitization in the exaggerated alpha 1b-adrenergic receptor-mediated inositol phosphate response in the aorta of the deoxycorticosterone acetate (DOCA)-salt rat model of hypertension. The basal accumulation of inositol phosphates and the basal incorporation of [3H]myo-inositol in the phosphatidylinositol lipid pool were significantly higher in the aorta of these hypertensive rats. A positive correlation (r = .88, P < .01) was demonstrated between basal inositol phosphate levels and the [3H]myo-inositol-labeled phosphatidylinositol lipid pool. In hypertensive rats, alpha 1b-adrenergic receptor-mediated inositol phosphate production in response to phenylephrine was significantly higher compared with normotensive rats. Despite the normalization of phenylephrine-mediated inositol phosphate production to the [3H]myo-inositol-labeled phosphatidylinositol lipid pool, the alpha 1b-adrenergic response remained significantly higher in the hypertensive rats. Phorbol ester activation of protein kinase C attenuated to a lesser extent phenylephrine-mediated inositol phosphate production (40%) in the aorta of hypertensive rats compared with the 80% attenuation observed in the aorta of normotensive rats. This desensitization was inhibited in both groups by the protein kinase C inhibitor staurosporine. The blunted desensitization of the alpha 1b-adrenergic receptor by protein kinase C activation was not associated with a decrease in protein kinase C activity in the hypertensive rats, because aortic strips from these animals were more responsive to phorbol ester activation than aortic strips from normotensive animals.(ABSTRACT TRUNCATED AT 250 WORDS)
Calderone
A
A
Faculty of Medicine, Department of Physiology, Université de Montréal, Québec, Canada.
Oster
L
L
Moreau
P
P
Rouleau
J L
JL
Stewart
D J
DJ
de Champlain
J
J
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000503:physiopathology; D003900:Desoxycorticosterone; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D010716:Phosphatidylinositols / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D012016:Reference Values; D012965:Sodium Chloride; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000470:Alkaloids; D010716:Phosphatidylinositols; D011942:Receptors, Adrenergic, alpha; D003900:Desoxycorticosterone; D012965:Sodium Chloride; D011493:Protein Kinase C; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate