Contractile Response To Hypoxia In The Porcine Coronary Artery

Abstract

The contractile response to hypoxia has been studied in the lung, and is termed hypoxic pulmonary vasoconstriction. However this response is also observed in coronary arteries. The present study investigated the mechanism underlying this contractile response in isolated porcine coronary arteries. Isometric tension was measured in rings with or without endothelium. In quiescent preparations, the contractile response to hypoxia was only observed in rings with endothelium and was abolished by indomethacin and terutroban, which shows the involvement of cyclooxygenase products and TP receptor activation, respectively, in this phenomenon. In contracted preparations, the hypoxic response was also endothelium-dependent, but was abolished by L-NAME and ODQ, suggesting the involvement of cyclic GMP. Assay of the cyclic GMP content showed no change upon exposure to hypoxia in preparations with and without endothelium. These experiments suggest that these hypoxic coronary contractions depend on more than one signaling pathway.