AJP - Regulatory, Integrative and Comparative Physiology, Vol 238, Issue 5 406-R412, Copyright © 1980 by American Physiological Society
Calcitonin stimulation of urine flow and sodium excretion in the starling
N. B. Clark and R. F. Wideman Jr
Renal effects of synthetic salmon calcitonin (CT) were examined in normal
and parathyroidectomized (PTX) starlings, Sturnus vulgaris. Standard
clearance studies were performed. Anesthetized birds were infused with
[14C]-inulin in 2.5% mannitol containing either 0.25% gelatin alone as a
control, or gelatin plus CT (2 IU CT/h; Armour). In intact starlings, CT
significantly increased urine flow and relative clearance of sodium
(CNa/CIn). CCa/CIn was significantly elevated only 40 min after start of
hormone infusion. No significant change occurred in CK/CIn, CPO4/CIn or in
serum levels of Na, K, Ca, or PO4. In PTX starlings, CT induced
significantly higher CNa/CIn. Urine flow was significantly higher at 40 and
60 min, whereas CK/CIn increased significantly only 20 min following start
of CT infusion. Serum calcium decreased significantly 1 h after hormone
administration and was accompanied by increased incidence of tetany. Serum
phosphate levels were significantly lower than those of corresponding PTX
controls 1 h post-CT, indicating that CT prevented the expected
hyperphosphatemia. Higher CT dose (20 IU/h) in PTX birds substantially
enhanced urine flow, CNa/CIn, CK/CIn, and occurrence of tetany.
