Enhanced responsiveness to ganglioplegic drugs occurring during short-term treatment with chlorothiazide has been attributed to increased vasomotor tone evoked by oligemia.1 Diuretic-induced oligemia also seems responsible for increased depressor responses to trimethapan (Arfonad) and decreased pressor responses to norepinephrine.2 Chlorothiazide alone can lower arterial pressure in some hypertensive patients,1-3 and this effect may result from a decrease of plasma volume. This report describes the oligemic and antihypertensive effects of the diuretic in hypertensive patients receiving the drug for varying periods. The results support the suggestion 1 that decreases of arterial pressure observed during short-term diuretic therapy result from decreases of plasma volume and not from a specific antihypertensive effect.
Studies were performed in 17 hypertensive patients hospitalized in the Research Ward of the Cleveland Clinic Hospital. Fifteen received a 100 mEq. sodium diet, and two—who had previously suffered from congestive cardiac failure—continued to take a 55