Acute effect of endogenous calcitonin on rat renal function.
To evaluate the physiological role of calcitonin (CT) in the renal Ca transport, increasing Ca concentrations (0-7.5 mM) were administered to thyroparathyroid-intact rats to provoke parathyroid hormone suppression and CT secretion. These groups of rats were compared to acutely thyroparathyroidectomized (TPTX) rats also infused with increasing Ca concentrations to produce comparable plasma Ca levels. A parathyroidectomized group was also studied. The presence of a high CT level was associated with a reduced fractional Ca excretion when compared to a TPTX group with a similar ultrafiltered Ca level (5.3 +/- 0.4 as compared with 10.6 +/- 0.4%; p < 0.01). The fractional Mg excretion was similarly reduced by endogenous CT (26.8 +/- 0.9 as compared with 37.3 +/- 2.1%; p < 0.01). The glomerular filtration rate was increased by CT, although the filtration fraction was unchanged. Because of changes in filtered Ca load due to an elevated glomerular filtration rate, comparison of TPTX and intact groups with comparable filtered Ca loads again demonstrated greater absolute Ca and Mg reabsorption in the presence of CT. Therefore, these studies that evaluated the effect of endogenous secretion of CT on nephron function confirm more recent studies using exogenous CT (human and salmon) that had suggested that CT is a renal Ca-conserving hormone like parathyroid hormone.
Carney
S L
SL
Faculty of Medicine, University of Newcastle, Callaghan, N.S.W., Australia.
D000042:Absorption; D000818:Animals; D002116:Calcitonin / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D007668:Kidney / Q000502:physiology*; D008274:Magnesium / Q000378:metabolism; D008297:Male; D009994:Osmolar Concentration; D016105:Parathyroidectomy; D010710:Phosphates / Q000652:urine; D051381:Rats; D017208:Rats, Wistar; D013965:Thyroidectomy; D013997:Time Factors; D014462:Ultrafiltration
D010710:Phosphates; D002116:Calcitonin; D008274:Magnesium; D002118:Calcium