Effects of the aminopeptidase P inhibitor apstatin on bradykinin-induced inositol 1,4,5-triphosphate in neonatal rat cardiomyocytes

We investigated the effect of apstatin (an aminopeptidase P inhibitor) on bradykinin-induced inositol 1,4,5-triphosphate (IP3) formation and glucose uptake in isolated neonatal rat cardiomyocytes. Apstatin enhanced bradykinin-induced IF, formation in a dose-dependent manner. We found that muM Hoe 140 (a bradykinin B-2-receptor antagonist) significantly decreased the potentiation of bradykinin-induced IP3 production by 5 muM apstatin from 781.8 +/- 67.2 to 127.4 +/- 33.0 pmol/mg protein; 5 muM apstatin increased bradykinin-induced glucose uptake from 197.0 +/- 25.5 to 297.3 +/- 64.0 pmol/h per milligram of protein. The stimulation of glucose uptake with apstatin was blocked to 132.5 +/- 26.2 pmol/h per milligram of protein by 1 muM Hoe 140. We conclude that apstatin stimulates bradykinin-induced IP3 formation and glucose uptake by preventing the degradation of bradykinin.