Marinobufagenin may mediate the adverse impact of salty diets on renal calcium retention by impairing the efficiency of renal tubular sodium-calcium exchange.
For reasons yet to be clarified, salt loading and plasma volume expansion decrease renal calcium retention; consequently, high-salt diets are thought to increase risk for osteoporosis and renal stones. These measures also can evoke increased adrenal production of the natriuretic factor marinobufagenin (MBG), recently implicated in the genesis of essential hypertension. MBG achieves natriuresis via potent selective inhibition of the alpha-1-type sodium pump, expressed throughout the nephron. In as much as renal calcium retention is largely dependent on efficient activity of calcium-sodium exchangers situated in the basolateral membranes of tubular epithelium, it is evident that an increased intracellular sodium concentration consequent to sodium pump inhibition could blunt the activity of these exchangers. Thus, it is postulated that MBG mediates the impact of salt loading on renal calcium retention.
McCarty
Mark F
MF
Pantox Laboratories, 4622 Santa Fe Street, San Diego, CA 92109, USA. mccarty@pantox.com
D002018:Bufanolides / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D006801:Humans; D017136:Ion Transport; D007684:Kidney Tubules / Q000187:drug effects* / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D017673:Sodium Chloride, Dietary / Q000009:adverse effects* / Q000037:antagonists & inhibitors*
D002018:Bufanolides; D017673:Sodium Chloride, Dietary; C093896:marinobufagenin; D012964:Sodium; D002118:Calcium