Distribution of Atrial Natriuretic Peptides in the Sand Rat (Psammomys Obesus) in Comparison to That in the Rat

Atrial natriuretic peptides (ANP) are a family of humoral compounds involved in water and salt homeostasis. Immunoreactive ANP (IR-ANP) was determined in the plasma and tissues of the rat and the sand rat (Psammomys obesus) using sensitive and specific radioimmunoassay. IR-ANP from the rat and the sand rat elute at identical retention times from reverse phase HPLC indicating that the same chemical entity is present in both species. IR-ANP highest levels were found, in both species, in the heart but it was also present in the adrenal gland, lung, kidney, liver, plasma and several loci in the central nervous system. The IR-ANP levels in the heart, adrenal gland, kidney, liver, cerebellum and cerebral cortex were lower in the sand rat compared to the rat. The plasma IR-ANP level of the diabetes-resistant sand rat was further decreased to about 10% of the level in the diabetes-resistant sand rat.