EN
We have investigated whether tyrosine kinases modify the activity of voltage-dependent Ba2+ currents (IBa) recorded from guinea-pig gastric myocytes by use of patch-clamp techniques. All experiments were carried on single smooth muscle cells, dispersed from the circular layer of the guinea-pig gastric antrum. Genistein (10 µM), a specific tyrosine kinase inhibitor, reduced the peak amplitude of IBa in a voltage- and concentration-dependent manner. Daidzein (30 µM), an inactive analog of genistein, also inhibited IBa in a concentration-dependent manner. Similarly, other types of tyrosine kinase inhibitors (lavendustin A and tyrphostin 23) suppressed the peak amplitude of IBa in a concentration-dependent manner. These results indicate that tyrosine kinases may be essential to regulate Ca2+ mobilization through voltage-dependent Ca2+ channels in gastric myocytes.