Oscillation of Blood Flow and Vascular Resistance During Mayer Waves

In cats anesthetized with chloralose, Mayer waves developed following graded hemorrhage and, in some, partial carotid occlusion. The average Mayer wave was 56 mm. Hg in amplitude rising from a base systemic pressure of 70 mm. Hg at a frequency of 3.0 per minute. Rhythmic fluctuation of respiratory depth and frequency paralleled but slightly preceded the blood pressure change. There was no significant variation in heart rate during Mayer waves. Flow in the abdominal aorta and vena cava varied inversely with systemic pressure. A flow lag of four to six seconds in the vena cava behind that in the aorta during Mayer waves was probably related to circulation time. Blood flow was measured in muscle, small intestine, skin, and kidney. During the pressure rise of each Mayer wave, blood flow decreased in muscle more than in gut. Cutaneous flow increased moderately. Renal flow varied directly with the arterial pressure. Changes vascular resistance were evaluated by holding perfusion pressure constant and measuring regional blood flow. During Mayer waves, muscle vascular resistance increased 276 per cent, intestinal resistance increased 210 per cent, and cutaneous resistance rose 136 per cent. Renal vascular resistance did not change. Since Mayer waves are apparently reflexogenic in origin, the data are interpreted as evidence for regional differences in the pattern of central reflex control of the peripheral vascular system.