Modulation of the L-type Ca-channels by insulin treatment in rat aorta.
Intracellular Ca2+ is a major regulator of vascular smooth muscle force generation. Because of this important role, the concentration of Ca2+ within the cell is tightly regulated by means of sequestration and extrusion transport processes. Insulin was found to increase the plasmalemma Ca-ATPase expression. In this work we have found that the expression of the L-type calcium channels, which are known to play an important role in the regulation of vasoconstriction and vasodilatation, is affected by insulin. We have found that single injection of insulin selectively decreased the Ca-channel expression in 150 min. Passive Ca-transport into proteoliposomes of plasma membrane proteins from the rat aorta was also decreased in 150 min, while after a longer resting period the Ca-transport was comparable to that from the control group. When insulin was added in vitro directly to a reaction mixture, an increase in the Ca-transport was found. No changes in Na/K-ATPase, which functions as cotransport system with Na/Ca exchanger, were observed. On the contrary, seven insulin injections and a subsequent 2.5 hour rest did not cause changes in the Ca channel expression. In the animals treated seven times with insulin, the decrease in the Ca-transport was delayed compared to single insulin injection. Our results suggest that insulin affects L-type calcium channels in the rat aorta by a decrease in the Ca-channel expression.
Thurzová
M
M
Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia.
Kvetńanský
R
R
Krizanová
O
O
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D066298:In Vitro Techniques; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology*; D017136:Ion Transport / Q000187:drug effects; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000502:physiology; D014664:Vasodilation / Q000502:physiology
D015220:Calcium Channels; D017931:DNA Primers; D007328:Insulin; D002118:Calcium