Action of mibefradil and lacidipine on the isolated human anterior tibial artery.
In isolated human anterior tibial artery the effects of two different types of calcium channel antagonists, mibefradil (a selective T-type Ca2+ channel antagonist) and lacidipine (a 1,4 dihydropyridine Ca2+ channel antagonist, acting at L- and T-type, but binds preferentially at L-type Ca2+ channels) were compared. Both drugs reduced the contractions of isolated arteries induced by 60 mM KCl. The potency (IC50) of mibefradil was 6.5 microM and of lacidipine 82.4 nM. The potencies of both Ca2+ channel antagonists differed significantly (p<0.001 at 0.1 and 1 microM; p<0.01 at 10 microM). Lacidipine was 79-times more effective than mibefradil in reducing the vasoconstriction in isolated human anterior tibial artery. One of the reasons for higher potency of lacidipine could be a higher density of L-type than of T-type Ca2+ channels in tissue of the human anterior tibial artery.
Martinuc
J
J
University of Ljubljana, Faculty of Medicine, Department of Pharmacology and Experimental Toxicology, Slovenia.
Drevensek
G
G
Budihna
M V
MV
D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004095:Dihydropyridines / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D020748:Mibefradil / Q000494:pharmacology*; D009994:Osmolar Concentration; D011189:Potassium Chloride / Q000494:pharmacology; D016909:Tibial Arteries / Q000187:drug effects* / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D002121:Calcium Channel Blockers; D004095:Dihydropyridines; D014662:Vasoconstrictor Agents; C060285:lacidipine; D020748:Mibefradil; D011189:Potassium Chloride