Ca2(+)-dependent and independent mechanisms of sustained contraction in vascular smooth muscle of rat aorta.
Norepinephrine (NE), prostaglandin F2 alpha (PG), 12-deoxyphorbol 13-isobutyrate (DPB) and high K+ induced sustained increase in cytosolic Ca2+ [( Ca2+]i) and muscle tension in rat aorta. Verapamil, at the concentration which abolished the high K(+)-induced changes, also abolished the increase in [Ca2+]i due to NE, PG and DPB although contractions were only partially inhibited. Excess EGTA further decreased [Ca2+]i although a part of the contraction was not inhibited. These results indicate that the sustained contractions induced by NE, PG and DPB are due to increase in [Ca2+]i, increase in Ca2+ sensitivity of contractile elements, and a Ca2(+)-independent mechanism.
Ozaki
H
H
Department of Veterinary Pharmacology, Faculty of Agriculture, University of Tokyo, Japan.
Ohyama
T
T
Sato
K
K
Karaki
H
H
D000818:Animals; D001013:Aorta, Thoracic / Q000502:physiology; D002118:Calcium / Q000502:physiology*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D015237:Dinoprost / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D010703:Phorbol Esters / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014700:Verapamil / Q000494:pharmacology
D010703:Phorbol Esters; C039067:12-deoxyphorbol 13-isobutyrate; D004533:Egtazic Acid; D015237:Dinoprost; D014700:Verapamil; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine