THE EFFECT OF THE UPRIGHTPOSTURE UPON HEPATIC BLOOD FLOW IN NORMOTENSIVE ANDHYPERTENSIVE SUBJECTS 1 By

The upright posture imposes a strain upon the cardiovascular system, chiefly as a result of its hydrostatic effects in the lower half of the body which, if unopposed, tend to produce hypotension in the upper half. These hydrostatic effects normally are counteracted by autonomic vasomotor adjustments, particularly in the splanchnic region. For example, the upright posture in man usually causes a reduction of renal blood flow (2). However, as yet no direct evidence has been reported concerning its effects upon the largest remaining portion of the splanchnic circulation, namely that draining through the liver. The present communication reports measurements of "hepatic blood flow" obtained with the bromsulfalein (BSP) extraction method (3) in normotensive and hypertensive subjects studied in the supine, in the upright, and again in the supine position.