Influence of extracellular calcium and calcium antagonists on contractions induced by potassium and prostaglandin F 2α in isolated cerebral and mesenteric arteries of the cat

• Published in: British journal of pharmacology Vol. 79; no. 1; pp. 135 - 140
• Main Authors: Andersson, K.‐E., Edvinsson, L., MacKenzie, E.T., Skärby, T., Young, A.R.
• Format: Journal Article
• Language: English
• Published: 01.05.1983
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1111/j.1476-5381.1983.tb10505.x

The effects of a number of calcium antagonists (diltiazem, nifedipine, nimodipine and verapamil) have been studied on feline isolated pial arteries contracted by potassium (127 m M ) or prostaglandin F 2α (PGF 2α , 2.5 μ M ) and mesenteric arteries contracted by potassium (127 m M ). Withdrawal of Ca 2+ from the extracellular medium for 30 min reduced the contractile response to potassium in cerebral vessels by 92% and in mesenteric vessels by 96%. Subsequent addition of Ca 2+ caused reproducible contractions which were inhibited by both nifedipine and nimodipine. The four calcium antagonists relaxed the isolated middle cerebral artery contracted either by potassium or PGF 2α , and mesenteric arteries contracted by potassium, in the following order of potency: nimodipine > nifedipine > verapamil > diltiazem. Nimodipine was more potent than nifedipine in cerebral arteries, and more potent in cerebral than in mesenteric arteries. Otherwise, the potassium‐contracted cerebral and mesenteric vessels showed no major differences in sensitivity to calcium antagonists.