Abstract
Inhibitory effects of calcium channel agonists such as Bay K 8644 [methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)- pyridine-5-carboxylate] and CGP 28392 [ethyl-4-(2-difluoromethoxyphenyl)-1,4,5,7-tetrahydro-2-methyl- 5-oxofuro-(3,4-b)-pyridine-3-carboxylate] on renin release were investigated, using rat kidney cortical slices. Bay K 8644 or CGP 28392 alone had no effect on renin release from the slices, whereas both compounds produced a concentration-dependent inhibition of the release in the presence of 15 mM potassium. The Bay K 8644-induced inhibitory action was more effective and potent than that seen with CGP 28392. Bay K 8644 caused a leftward shift of the dose-response curve of the potassium-induced decrease in renin release. In contrast, the dose-response relationships of the release to norepinephrine and methoxamine were not affected by Bay K 8644. The combination of the maximum effective doses of calcium channel agonists and norepinephrine exerted an apparent additive effect on the release of renin. The inhibitory effects of Bay K 8644 and CGP 28392 were attenuated in the presence of decreased extracellular calcium concentrations. Nifedipine and verapamil elicited a blocking action on the inhibition of renin release by Bay K 8644 or CGP 28392, in a concentration-dependent manner. Calmodulin antagonists, such as trifluoperazine and calmidazolium suppressed significantly the decreasing effect of Bay K 8644 or CGP 28392 on renin release from the slices.(ABSTRACT TRUNCATED AT 250 WORDS)
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|