THE EFFECT OF SHORT-TERM EXERCISE ON PLASMA VOLUME AND BLOOD PRESSURE IN GUANETHIDINE-TREATED HYPERTENSIVES

Short-term exercise produced a decrease in plasma volume and a rise in B.P. in normotensives and untreated hypertensive patients. The decrease in plasma volume is presumably due to an increased intra-capillary pressure in the contracting muscles. In guanethidine-treated patients there was no change in plasma volume during exercise, probably because of vasodilatation and decreased intra-capillary pressure in the contracting muscles. In several of the guanethidine-treated patients B.P. fell during and after exercise, in some cases so markedly that symptoms of cerebral ischemia developed.