Endostatin inhibits T-type Ca2+ channel current in guinea pig ventricular myocyte.

Endostatin, a fragment of collagen XVIII, is known as an endogenous angiogenesis inhibitor, and its serum concentration increases in various cardiovascular diseases. T-type Ca(2+) channel, low voltage-activated Ca(2+) channel, is not expressed in adult ventricular myocytes. Re-expression of T-type Ca(2+) channels in cardiac myocytes is thought to be involved in the development of cardiac hypertrophy. We examined the effects of endostatin on T-type Ca(2+) channel current by whole-cell patch clamp technique in freshly isolated adult guinea pig ventricular myocytes, which exceptionally express T-type Ca(2+) channels. Although endostatin 300 ng/ml had no effect on L-type Ca(2+) current, it significantly inhibited T-type Ca(2+) current. These data indicate that endostatin can be an endogenous inhibitor of T-type Ca(2+) channels in the cardiac myocytes.