A modification of Jeffers method for estimating antidiuretic hormone in body fluids is described. With this modification it is possible to detect antidiuretic activity corresponding to 0.25 μU of Vasopressin.

Vasopressin studies in the rat. IV. The vasopressin-water-equivalent and vasopressin clearance by the kidney.

Effects of a dry diet on the hypothalamic neurohypophyseal neurosecretory system in spiny mice as compared to the albino rat and mouse.

1) Plasma ADH levels measured by bioassay in the group with extracorporeal circulation were 2.3 ± 0.6 μu/ml before surgery and 6.6 ± 1.8 μu/ml during anesthesia. They increased to 196.5 ± 62.3 μu/ml or about 100 times greater than before surgery during cardiopulmonary bypass. 2) In the group without extracorporeal circulation, plasma ADH levels were 1.5 ± 0.9 μu/ml before surgery and increased to 44.1 ± 15.2 μu/ml during operation. 3) After operation decrease in plasma ADH level was relatively rapid in both groups. It became three times that of the control level in the morning of the next day. 4) Marked increase in plasma ADH level during cardiopulmonary bypass was much the same as it was during hemorrhagic shock in dog experiments. 5) Fall in mean arterial blood pressure and loss of pulsatile blood flow will play main roles in this marked increase in ADH during cardiopulmonary bypass through stimulation of arterial baroreceptors and probably chemoreceptors. 6) In two cases with mitral stenosis, increase in plasma ADH during cardiopulmonary bypass was lesser than the other heart diseases.

Plasma ADH levels during heart surgery.

The regulation of kidney function by both volume and osmotic pressure of the blood involves the ADH mechanism. When the two reflex mechanisms compete, the response of the kidney depends on the magnitude of the blood volume. If blood volume is reduced even to a very slight degree, volume control supervenes and water is retained in excess of salt. In the control of volume the afferent impulses from the baroreceptor zones of the circulation play an important role. Since these receptors are not only sensitive to the magnitude of bloodvolume, but also to changes in respiration and cardiac activity it is suggested that volume control is only part of a more complicated mechanism for the defense of an adequate cardiac performance.

Otto H. Gauer

Papers

Reflex control of the excretory function of the kidney