Modification of renal and tissue cation transport by cholecystokinin octapeptide in the rabbit.
1. Reports that gastric sodium loads cause a greater natriuresis than those administered intravenously, suggest that a gastric or portal sodium monitor exists which releases a humoral natriuretic factor. To determine whether cholecystokinin octapeptide (CCK-8) had direct renal natriuretic effects (and was therefore a candidate for this gut-derived natriuretic factor) we compared the natriuretic response to CCK-8 infused intravenously with that infused directly into the renal artery of six conscious male rabbits. 2. CCK-8 produced a significant log dose-dependent decrease in the fractional excretions of calcium (P less than 0.05) and magnesium (P less than 0.005) and a log dose-dependent increase in fractional sodium excretion (P less than 0.025). The significant decreases in the fractional excretions of calcium and magnesium were accompanied by log dose-dependent falls in their plasma levels (calcium, P less than 0.05, and magnesium, P less than 0.005), indicating movement of calcium and magnesium to extravascular sites. Studies of tissue calcium and magnesium levels in response to CCK-8 infusion showed that calcium accumulated in kidney and skeletal muscle. 3. We conclude that CCK-8 has direct renal natriuretic effects at the tubular level and could be the gut-derived natriuretic factor. In addition to its effects on sodium excretion, CCK-8 causes renal retention and increased gut absorption of calcium and magnesium with movement of these ions to extravascular sites.
Duggan
K A
KA
Department of Nephrology, Prince Henry Hospital, Sydney, N.S.W., Australia.
Hams
G
G
MacDonald
G J
GJ
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002412:Cations / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006439:Hemodynamics / Q000187:drug effects; D007261:Infusions, Intra-Arterial; D007262:Infusions, Intravenous; D007668:Kidney / Q000098:blood supply / Q000187:drug effects*; D008274:Magnesium / Q000378:metabolism; D008297:Male; D009318:Natriuresis / Q000187:drug effects; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D012077:Renal Artery; D012844:Sincalide / Q000008:administration & dosage / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism
D002412:Cations; D012964:Sodium; D008274:Magnesium; D012844:Sincalide; D002118:Calcium