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Comparative studies of the role of endothelin (ET) B-type receptor in the phosphoinositide turnover signaling in cultured aortic endothelial cells of the Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) strains of hypertensive rat models reveal that ET receptor-mediated signal transduction is higher in the SHR strain than in the WKY strain. The mobilization of Ca(2+) from intracellular stores stimulation of protein kinase C is higher in SHR-based cells than in WKY-based cells after ET-3 addition.

Adenylate cyclase assays, tissue cultures and cAMP measurements in the vascular smooth muscle cells of rats show that sodium chloride and glucocorticoid regulate the dopamine DA1 receptors through different mechanisms and cause low adenylate cyclase function and low receptor affinity, and high cyclase activity and receptor activity. Glucocorticoid elevates cAMP response to dopamine to increase receptor activity and adenylate cyclase affinity. Glucocorticoid antagonist or cyloheximide inhibit the glucocorticoid's effect on the DA1 receptors.

Endothelin regulates the mitogenic effect of platelet-derived growth factor (PDGF) on glomerular mesangial cells. The PDGF isoforms, AB and BB, activate endothelin-1 (ET-1) secretion in mesangial cells through PDGF beta-receptors. Endogenously-produced ET-1 regulates the mitogenic effect of PDGF AB and BB through A-type endothelin (ETa) receptors in cells. Treatment of rats with ETa receptors decreases renal mass limited glomerular damage and inhibits renal function impairment.

Chronic treatment with enalapril and MK-954 decreases the ventricular weight and systolic blood pressure in deoxycorticosterone acetate salt-induced spontaneously hypertensive rats. The plasma concentrations of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are reduced, but not to the levels seen in Wistar-Kyoto rats. Hydralazine causes enhanced ANP and BNP plasma concentrations when compared to enalapril and MK-954.

The effects of natriuretic peptides (NP) on the secretion of endothelin-1 (E-1) was studied in the mesangial cells of rat kidney glomerulus. Atrial NP and brain NP inhibits excessive excretion of E1 on contraction of mesangial cells and glomerular microcirculation by induction of ET-1 secretion by arginine vasopressin. C-type NP also inhibited EP-1 secretion to a lesser degree compared to ANP and BNP.

The roles of protein kinase C, dopamine DA-1 receptors and cyclic adenylic acid (cAMP) in vasodilation and blood pressure regulation were investigated. The study protocol involved examination of the interaction between a phorbol ester and DA-1 receptors in rat vascular smooth muscle cells. The results indicate that protein kinase C induces an increase in the expression of DA-1 receptors, thus enhancing receptor-coupled generation of cAMP.