Reactivity to Pressor Agents in Hypertension

Abstract

The pressor responses to intravenous injections of angiotonin and s-methyl iso -thiourea have been studied in 50 hypertensive subjects and 20 normotensive controls. The rises of blood pressure in the two groups were similar, being but slightly greater in the hypertensives. After the blood pressure has been reduced with hexamethonium, however, the pressor responses to angiotonin, s-methyl isothiourea and noradrenaline are much greater in hypertensives than normotensive subjects. The responses under these conditions to all three pressor agents run parallel to each other, suggesting that there is no specific increase in reactivity in hypertensive subjects, either to angiotonin or noradrenaline. It has been concluded that there is evidence of increased reactivity to pressor substances in hypertensive subjects but that this is not demonstrable until the blood pressure control mechanisms have been inactivated by hexamethonium.