Absence of renin secretion in the portal venous system in rats

A new technique for hepatic portal vein catheterization in freely moving rats

To perform kinetic studies of pancreatic hormones in freely moving rats, we have designed a new technique for hepatic portal vein catheterization through the left branch of the portal vein. Rats were followed up for 14-38 days. Catheter patency allowed blood sampling in 86% of rats on postoperative day 8 and in 55% on day 12. Rat growth, liver functions, and regional blood flows (measured with radiolabeled microspheres) were normal. In freely moving rats fasted for 16 h, portal venous concentrations in the basal state were: glucose, 112 +/- 4 mg/dl; insulin, 67 +/- 10 microU/ml; and glucagon, 480 +/- 74 pg/ml. These values remained stable for a 1-h period. Intravenous glucose infusion induced a biphasic insulin release, significant from the 1st min of infusion on, and a significant decline in glucagon level. Intravenous arginine stimulated both A and B cells. The portoperipheral hormone concentration gradient, which was detected in the basal state, increased during arginine infusion, particularly in regard to insulin. Ingestion of a mixed meal induced an early glucagon release and a sustained rise in insulin and glucose concentrations.

Aggression-provoked renin release from extrarenal and extrasubmaxillary sources in mice

In submaxillary sialoadenectomized and nephrectomized mice aggressive behaviour provoked 5 to 40-fold increases in plasma renin concentration. The changes in renin concentration with time were different in different groups of confronted mice with only partial correlation between the pattern and the observable degree of fight. The changes were similar in sialoadenectomized mice with untouched kidneys as in sialoadenectomized and nephrectomized, indicating that aggression causes no measurable, if any, renal renin release. Repeated aggression with 2 hourly intervals provoked repeated renin release from extrarenal and extrasubmaxillary sources. The renin concentrations of different organs showed the same mutual relationship as in other mammals, but were about 10-fold higher. Splenectomy was without effect on the aggression-provoked renin release. Antibodies against pure mouse renin neutralized the renin in plasma and organs, which contained only insignificant, if any, pepsin activatable inactive renin. Adrenaline, apomorphine, carbachol and dihydralazine were as isoprenaline and noradrenaline without effect on renin release in sialoadenectomized and nephrectomized mice.

[Effect of urethane and penthobarbital on the behaviour of the renin-angiotensin-system in rat (author's transl)]

The behaviour of the renin-angiotensin-system was investigated after urethane and penthobarbital anaesthesia in rats. The recent results support the early observation that urethane increases the plasma-renin-activity and the haematocrit. It was further shown that urethane in the customary anaesthetic dose causes hypoproteinaemia and a decrease in the pressor response to angiotensin and in renin substrate concentration. Based on these results, its use as an anaesthetic in experiments connected with the renin-angiotensin-system does not appear to be appropriate.

Iso-renin of extrarenal origin. "The tissue angiotensinogenase systems"

Enzymes, similar to kidney renin, are present in extrarenal tissue of most mammals; they hydrolyze angiotensinogen to form angiotensin I. We suggest that these enzymes be called angiotensinogenases. Angiotensinogenase concentrations in extrarenal tissue can exceed those in the kidney. The enzyme has been obtained in pure crystalline form. Angiotensinogenases are part of a complex enzyme system which leads to local production of angiotensin. Results indicating a biologic role of the angiotensinogenase system in brain, adrenal gland, uterus and tissue culture are discussed.