Pressor responses to noxious stimuli in hypertensive patients. Effects of reserpine and chlorothiazide.

CLINICALi STUDIES of hypotensive drugs have been concerned primarily with the effects of these agents on basal or casual levels of blood pressure. Little attention has been given to alterations in the reactivity of the blood pressure to noxious stimuli during the course of chronie drug therapy. Persistent reactivity in treated patients is iiuplied fronm such data as those indicating that blood pressures in treated patients frequently are lower when measured at home than during clinic or office visits.' Moreover, in view of the hypersensitivitv of denervated organs,2 drugs that inhibit the autonomnic nervous system might even exaggerate the pressor response to any stimiiulus that may act through a humoral, rather than a neuro-genic mechanism. Data pertinent to this problenm were obtained during the course of a previous study in which the pressor responses of hypertensive patients to a number of different noxious stimuli were evaluated.3 Subjects had been ineluded in this study who were receiving several different types of drug therapy. Although increased reactivity to both psychological and physical stimuli was demonstrated in the hypertensive group as a whole, patients receiving drugs at the time of testing showed responses quantitatively similar to those of untreated subjects. Accordingly, the present study was designed specifically to compare the pressor response in the same patient before and during therapy, in order to obtain systematic information about the effects of certain hypotensive drugs on reactivity. Thirty hypertensive patients with miild to miod-erate hypertensive vascular disease were divided into three groups of 10 each, and their pressor responses to noxious stimnuli were tested before and during therapy. One group reeeived reser-pine; a, second, chlorothiazide or onie of its con-geners; a third, a eomubination of both these drugs. The severity of the hypertension in each group is indicated in table 1, aiid the average dose and duration of therapy are shown in table 2. All patients were ambulatory and were seen regularly in the Hypertension-Renal Clinic throughout the study. The techiiies employed to test pressor responses have been described fully in the previous publication .3 Briefly, after a 30-minute rest period three noxious stimuli were administered at 15-to 30-minute intervals: (1) the intravenous injection of 10 ml. of normal saline during which the subject was asked to "count backwards from 100 as rapidly as possible"; (2) a standard cold pressor test; (3) the reading of a chart on which the names of colors were printed …