Evidence that the hypothalamus may be a source of a circulating Na+-K+-ATPase inhibitor.
Acetone extracts from a variety of rat tissues were tested for their ability to stimulate renal glucose-6-phosphate dehydrogenase (G6PD) activity at 2 min in an in-vitro cytochemical assay which is a marker of the sodium potassium-dependent adenosine triphosphatase (Na+-K+-ATPase) inhibiting activity. Extracts of the hypothalamus were the only ones found to be active in this system. Acetone extract of hypothalamus also inhibited renal Na+-K+-ATPase activity in vitro. The G6PD-stimulating activity from one hypothalamus was about 10000 to 100000 times greater than that of 1 ml plasma. The G6PD-stimulating activity of hypothalamic extracts from rats which had been on a high sodium intake for 4 weeks were approximately 150 times more active than those obtained from rats which had been on a low sodium diet. The G6PD-stimulating activity of the corresponding plasma was sixfold more active. These findings suggest that a circulating sodium transport inhibitor(s) may be secreted from the hypothalamus.
D000818:Animals; D001681:Biological Assay; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D006168:Guinea Pigs; D007031:Hypothalamus / Q000502:physiology*; D007668:Kidney / Q000187:drug effects / Q000201:enzymology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D014020:Tissue Extracts / Q000494:pharmacology*
D014020:Tissue Extracts; D012964:Sodium; D005954:Glucosephosphate Dehydrogenase; D000254:Sodium-Potassium-Exchanging ATPase