Inhibition of calcium entry preserves contractility of arterial smooth muscle in culture.
The addition of the growth stimulator fetal calf serum (FCS, 10%) to rings of rat tail artery causes an increase in [Ca2+]i, accompanied by contraction. This response was inhibited by the calcium entry blocker verapamil (1 microM). To investigate the effect of Ca2+ entry blockade on growth and contractility, rings of rat tail artery were cultured for 4 days in medium with or without FCS and then mounted for tension registration and stimulated with noradrenaline (NA) or high-K+ solution. In cultured rings growth was quantitated by [3H]-thymidine incorporation and increase in protein contents. FCS in the medium stimulated DNA synthesis by about 2-fold and increased protein contents by about 70%. The growth-stimulated cultured rings developed less force than freshly prepared rings (2.2 +/- 0.3 vs. 8.3 +/- 1.0 mN/mm). The addition of 1 microM verapamil to the medium during culture increased maximal NA-evoked force to 5.0 +/- 0.4 mN/mm but had no effect on the increases in DNA synthesis and protein contents. Force developed by growth-arrested rings, cultured in the absence of FCS, was not different from that of freshly prepared rings (7.2 +/- 0.6 mM/mm). Verapamil did not affect maximal force in these rings. Similar responses were seen when contraction was elicited by high-K+ solution. We conclude that verapamil, present during culture, preserves contractility of arterial smooth muscle, and that this effect is not parallel to inhibition of growth.
Lindqvist
A
A
Department of Physiology and Neuroscience, University of Lund, Sweden.
Nilsson
B O
BO
Hellstrand
P
P
D000818:Animals; D002118:Calcium / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D003470:Culture Media; D005260:Female; D006133:Growth Substances / Q000494:pharmacology; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009124:Muscle Proteins / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014700:Verapamil / Q000494:pharmacology
D002121:Calcium Channel Blockers; D003470:Culture Media; D006133:Growth Substances; D009124:Muscle Proteins; D014700:Verapamil; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine