Korean J Physiol Pharmacol.  2000 Apr;4(2):113-120.

Regulation of the contraction induced by emptying of intracellular Ca2+ stores in cat gastric smooth muscle

• Baek HJ
• Sim SS
• Rhie DJ
• Yoon SH
• Hahn SJ
• Jo YH
• Kim MS

Abstract

To investigate the mechanism of smooth muscle contraction induced by emptying of intracellular Ca2+ stores, we measured isometric contraction and 45Ca2+ influx. CaCl2 increased Ca2+ store emptying- induced contraction in dose-dependent manner, but phospholipase C activity was not affected by the Ca2+ store emptying-induced contraction. The contraction was inhibited by voltage-dependent Ca2+ channel antagonists dose dependently, but not by TMB-8 (intracellular Ca2+ release blocker). Both PKC inhibitors (H-7 and staurosporine) and tyrosine kinase inhibitors (genistein and methyl 2,5-dihydroxycinnamic acid) significantly inhibited the contraction, but calmodulin antagonists (W-7 and trifluoperazine) had no inhibitory effect on the contraction. The combined inhibitory effects of protein kinase inhibitors, H-7 and genistein, together with verapamil were greater than that of each one alone. In Ca2+ store-emptied condition, 45Ca2+ influx was significantly inhibited by verapamil, H-7 or genistein but not by trifluoperazine. However combined inhibitory effects of protein kinase inhibitors, H-7 and genistein, together with verapamil were not observed. Therefore, this kinase pathway may modulate the sensitivity of contractile protein. These results suggest that contraction induced by emptying of intracellular Ca2+ stores was mediated by influx of extracellular Ca2+ through voltage-dependent Ca2+ channel, also protein kinase C and/or tyrosine kinase pathway modulates the Ca2+ sensitivity of contractile protein.

MeSH Terms

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine
Animals
Calmodulin
Cats*
Genistein
Isometric Contraction
Muscle, Smooth*
Phosphotransferases
Protein Kinase C
Protein Kinase Inhibitors
Protein-Tyrosine Kinases
Trifluoperazine
Type C Phospholipases
Verapamil
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine
Calmodulin
Genistein
Phosphotransferases
Protein Kinase C
Protein Kinase Inhibitors
Protein-Tyrosine Kinases
Trifluoperazine
Type C Phospholipases
Verapamil