Studies on the juxtaglomerular apparatus. VI. Sympathetic innervation, catecholamines and the renin-angiotensin-system in rats and tree-shrews (Tupaia belangeri).

It has previously been reported that the primitive primate Tupaia belangeri develops a renal failure when exposed to psychosocial stress. In order to learn if this high susceptibility to stress of the Tupaia kidney can be correlated with morphological and functional parameters of the juxtaglomerular apparatus (JGA) and the renin-angiotension system, comparative experiments were performed on Tupaia and rat. Our results reveal an outstandingly high potency of the JGA and the renin-angiotensin system in Tupaia as evident from the following findings: The Tupaia JGA contains a great number of epithelioid cells abounding in renin granules (electron microscopy). The renin content of the Tupaia kidney is considerably higher than in the rat (radio-immunoassay). The sympathetic innervation of the kidney and especially of the JGA is abundant in Tupaia (fluorescence and electron microscopy). Catecholamine contents of the kidney and other organs are significantly higher in Tupaia than in rats (spectrophotofluorometry). Our results support the previously developed concept of a potent intrarenal neuroendocrine interaction at the JGA level favouring, under certain conditions of social stress, the development of acute renal failure in Tupaia belangeri.