[L-type calcium channels involvement in aortic smooth muscle contraction as revealed by membrane potential and active force dynamics].
Membrane potential (MP) is essential in smooth muscle (SM) contractile activity, mainly by its effect upon L-type Ca2+ channels. We simultaneously recorded SM isometric tension and MP in de-endothelised rat aorta rings and examined their submaximal activation by K+, norepinephrine (NE) or phenylephrine (PHE) and the influence of methoxyverapamil (D600). K+ -induced contraction strictly correlated with depolarization, while faster contractions induced by NE or PHE started and peaked with a less depolarized membrane. D600 completely relaxed K+ or NE contracted rings, time-correlated with full repolarization, but partially relaxed PHE-contracted rings, with partial repolarization, which did not precede relaxation. The observed MP and force dynamics support known mechanisms of action of the drugs used. L-type channels participate in the depolarizing and contractile effect of NE, as opposite to their minor involvement in the effects of PHE.
Serban
D N
DN
Universitatea de Medicină si Farmacie Gr.T. Popa Iaşi, Facultatea de Medicină, Disciplina de Fiziologie.
Serban
Ionela Lăcrămioara
IL
Petrescu
Gh
G
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000465:Algorithms; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000187:drug effects / Q000502:physiology*; D004338:Drug Combinations; D005711:Gallopamil / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D023421:Models, Animal; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011941:Receptors, Adrenergic / Q000187:drug effects
D000316:Adrenergic alpha-Agonists; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D004338:Drug Combinations; D011941:Receptors, Adrenergic; D010656:Phenylephrine; D005711:Gallopamil; D009638:Norepinephrine