Dependence of canine right coronary arterial flow upon heart rate and right ventricular pressure

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To elucidate the exact mechanisms for the right coronary artery (RCA) to cope with the overload, we studied nine open-chest adult Beagles and analyzed the flow signals of the RCA in relation to independently varied heart rate (pacing) and right ventricular pressure (pulmonary artery banding).Both increased heart rate and right ventricular pressure increased the total volume flow of the RCA.The diastolic over total flow ratio (D/T), however, enlarged on increasing right ventricular pressure while it declined on increasing heart rates. Our data confirmed, as well, that increased flow of RCA on rising heart rate was provided mainly by an increase in systolic phase, while the increase on augmented right ventricular pressure was provided by the increase in diastolic phase. The RCA manages to deliver blood to the right ventricular musculature in two different ways in response to increasing heart rate and ventricular pressure.Final conclusion from chronic experiments is not reached yet. We are left behind the schedule, partly because of some unavoidable alterations of situations around me. We are planning to do some more experiments according to the original protocol in 1996 to complete the study.