Endostatin inhibits bradykinin-induced cardiac contraction

.Endogenous fragments of extracellular matrix are known to possess various biologicaleffects. Levels of endostatin, a fragment of collagen type XVIII, increase in certaincardiac diseases, such as cardiac hypertrophy and myocardial infarction. However, theinfluence of endostatin on cardiac contraction has not been clarified. In the presentstudy, we investigated the effects of endostatin on bradykinin-induced atrial contraction.Isometric contractile force of mouse isolated left atria induced by electrical currentpulse was measured. Voltage-dependent calcium current of guinea pig ventricular myocyteswas measured by a whole-cell patch-clamp technique. Endostatin (100–1,000ng/ml) alone treatment had no influence on left atrialcontraction. On the other hand, pretreatment with endostatin (300ng/ml) significantly inhibited bradykinin (1µM)-induced contraction and voltage-dependent calcium current. Thesedata suggest that endostatin may decrease bradykinin-induced cardiac contraction perhapsthrough the inhibition of voltage-dependent calcium channel.