Seasonal kidney and plasma renin concentration in Testudo hermanni Gmelin

Comparative renal physiology of exotic species

In this article the osmoregulatory, acid-base homeostasis, and excretory functions of the renal system of invertebrates and vertebrates are reviewed. The mammalian renal system is the most highly evolved in terms of the range of functions performed by the kidneys. Renal physiology in other animals can be very different, and a sound knowledge of these differences is important for understanding health and disease processes that involve the kidneys, as well as ion and water homeostasis. Many animals rely on multiple organs along with the kidneys to maintain osmotic, ionic, and pH balance. Some animals rely heavily on postrenal modification of urine to conserve water and salt balance; this can influence the interpretation of disease signs and treatment modalities.

Osmotic stress, plasma renin activity, and spermatogenesis in Vipera aspis

Circulating electrolytes (Na+, K+), plasma renin-like activity, testosterone, and testis morphology were investigated in early summer during the spermatogenic progressive phase in Vipera aspis subjected to sodium loading and sodium depletion. After sodium loading, plasma sodium and plasma testosterone levels were significantly elevated compared with those of controls, while plasma renin-like activity was depressed, spermiogenesis was increased, the epithelium lining the epididymis was very thick, and the Leydig cells were hypertrophied. After sodium depletion, plasma sodium and plasma testosterone levels were significantly depressed and plasma renin-like activity was significantly elevated. Spermiogenesis seemed to be slightly regressed: the epithelium lining the epididymis was very thin, and the lumen was devoid of spermatozoa. The Leydig cells were hardly visible. All the data strongly suggest that osmotic stress affects gonadal activity in the snake. V. aspis.