Pressor Responses to Noxious Stimuli in Hypertensive Patients

The pressor and pulse rate responses to several standardized stimuli were determined in hypertensive patients receiving guanethidine sulfate or alpha methyldopa in therapeutic doses. Despite differences between the two compounds in their mode of action, both demonstrated functionally sympatholytic effects. Both drugs produced a greater blood pressure fall in the erect posture than in the supine and impaired the pressor response to the cold pressor test. The pressor reactivity to intravenous angiotensin, however, persisted. Responses to psychophysiologic stimuli were decreased. The implications of these findings for both therapy and for understanding of physiologic mechanisms of pressor reactivity are discussed.