Effects of temperature and Na0+ on the relaxation of phasic and tonic tension of guinea-pig ureter muscle.
Effects of temperature and Na0+ on the relaxation of guinea-pig ureter smooth muscle were studied. Relaxation of phasic contraction was found to be highly temperature-dependent, practically independent of Na0+ and Ca02+, and resistant to vanadate. The relaxation of the tonic tension of both high-K and low-Na contracture was less temperature-dependent and affected by Na0+. The relaxation of tonic tension produced by introduction of Na0+ was about 3-5 times faster than that produced by Ca-free solution. La3+ ions were found to block the relaxation of the tonic component of the Na+-free contracture initiated by removal of Ca02+. Three systems of regulation of cell calcium are suggested to be operative in the ureter muscle: a fast one which is highly temperature-dependent and responsible for the relaxation of the phasic contraction (probably the sarcoplasmic reticulum), and two slow membrane-linked carriers, one of which is dependent on Na0+ (probably Na-Ca exchange) and another one which is independent of Na0+ and inhibited by La3+ (probably Ca-pump).
Burdyga
T V
TV
Department of General Physiology, Kiev State Shevchenko University, USSR.
Magura
I S
IS
D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D009543:Nifedipine / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology*; D013696:Temperature; D014513:Ureter / Q000187:drug effects / Q000502:physiology*; D014638:Vanadates / Q000494:pharmacology
D002110:Caffeine; D014638:Vanadates; D012964:Sodium; D009543:Nifedipine; D002118:Calcium