Effects of Ca antagonists on Ca fluxes in resistance vessels

Journal Article · Thu Dec 31 23:00:00 EST 1981 · J. Cardiovasc. Pharmacol.; (United States)

DOI:https://doi.org/10.1097/00005344-198200433-00005· OSTI ID:6097824

Cauvin, C; Saida, K; van Breemen, C

Researchers have examined contractions and /sup 45/Ca fluxes induced by norepinephrine (NE) and 80 mM potassium (high K) depolarization and their inhibition by dilitazem in rabbit mesenteric resistance vessels. Contraction induced by both NE and high K depended almost completely on extracellular Ca. Dose-response curves for diltiazem inhibition of NE (10(-5) M) and high K contractions showed ED50 values of 1 X 10(-8) and 6 X 10(-7) M, respectively, indicating that the receptor-operated channel (ROC) was more sensitive than the potential-operated channel (POC) to the action of diltiazem. Diltiazem (10(-6) M) was shown to inhibit NE- and 80 mM K-stimulated /sup 45/Ca influx effectively by 87 +/- 15 and 85 +/- 10%, respectively. Comparison of these data to those obtained from aorta suggest that although the sensitivity of the POC is approximately the same in aorta and mesenteric resistance vessels, the sensitivity of the ROC is much greater in the latter. This increased sensitivity is paralleled by a greatly decreased role of intracellular Ca release in NE contraction in mesenteric resistance vessels.

• Research Organization: Department of Pharmacology, University of Miami School of Medicine, Florida
• OSTI ID: 6097824
• Journal Information: J. Cardiovasc. Pharmacol.; (United States), Journal Name: J. Cardiovasc. Pharmacol.; (United States) Vol. 4 Suppl 3; ISSN JCPCD
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
ALKALI METALS
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