PRESENCE OF ATRIAL-NATRIURETIC-PEPTIDE IN 2 DESERT RODENTS - COMPARISON WITH RAT

Atrial natriuretic peptide (ANP) was characterized and assayed in plas mas, hearts, and brains of two Algerian desert rodents, Psammomys abes us and Meriones libycus along with vasopressin, which was assayed in h ypophyses and hypothalami. Using reverse-phase high-performance liquid chromatography and radioimmunoassay, we showed, in plasmas and hearts of both species of desert rats, the presence of peptides similar to r at N- and C-terminal ANP but in lower amounts than in Wistar rats. Con versely, C-terminal ANP was abundantly detected in hypophyses from Mer iones libycus rats. As these peptides, through their diuretic and natr iuretic activities, are involved in body fluid regulation and electrol yte balance, the reduction of ANP stores in both plasmas and hearts su ggests that diuresis and natriuresis are lowered in both species of ma mmals adapted to arid environments. This could occur because of the va sopressin-mediated adaptation, but also in response to the low ANP inv olvement in hydro-osmotic regulations, even in Psammomys, which has a dietary salt loading. On the other hand, the higher C-terminal ANP con tents in the hypophysis of Meriones than in Psammomys and Wistar rats remain to be understood. (C) 1998 Elsevier Science Inc.