The effect of five per cent carbon dioxide on the response of muscle blood flow to isoproterenol in man

Abstract

Heart rate, muscle blood flow, and blood pressure were measured in 10 subjects. The administration of 5 per cent CO2 caused a fall in blood flow and an increase in mean arterial pressure without significant change in heart rate. An infusion of isoproterenol at a dose of 2 ug per minute caused an increase in flow, heart rate, and pulse pressure but no change in mean arterial blood pressure. The administration of 5 per cent CO2 during the isoproterenol infusion abolished the increase in muscle blood flow, produced an increase in mean arterial blood pressure, and caused an attenuation of the chronotropic effect of isoproterenol. These results suggest that certain cardiovascular effects of isoproterenol are altered during respiratory acidosis.