The early phase of calcipenia-induced parathyroid hormone secretion is blunted in vasculary perfused parathyroid glands of streptozotocin-diabetic rats.
OBJECTIVE
To study effects of diabetes mellitus on parathyroid hormone (PTH) secretion, the rat parathyroid glands were perfused via the bilateral carotic arteries.


METHODS
Diabetic rats showed plasma glucose levels above 30 mmol/l, but no change in plasma PTH concentration, 14 days after an administration of 70 mg/kg of streptozotocin. Krebs-Ringer bicarbonate buffer containing 0.1% bovine serum albumin was used for perfusate. Perfusate calcium was lowered from 2.5 mmol/l to 0.5 mmol/l.


RESULTS
In the normal rat parathyroid glands, PTH secretion was promptly evoked by calcipenia (from below 0.25 ng for 2.5 min in the perfusion with normal calcium to 0.73 +/- 0.17 ng during calcipenia time 0-2.5 min), and slightly decreased (0.51 +/- 0.12 ng during calcipenia time 2.5-5 min), and then increased (0.75 +/- 0.16 ng during calcipenia time 7.5-10 min). Diabetes abolished the early phase of PTH secretion (below 0.25 ng during calcipenia time 0-2.5 min), but did not affect the late phase of PTH secretion (0.64 +/- 0.14 ng during calcipenia time 7.5-10 min). Insulin treatment with 25 U/kg daily for 14 days completely normalized the early phase of PTH secretion.


CONCLUSIONS
It is suggested that an insulin-deficient diabetes, not quantitatively but qualitatively, impaires the PTH secretion.
Mokuda
O
O
Third Department of Internal Medicine, Teikyo University School of Medicine, Ichihara, Japan. mokuchan_14@yahoo.co.jp
Okazaki
R
R
Sakamoto
Y
Y
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002118:Calcium / Q000097:blood; D002339:Carotid Arteries; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000503:physiopathology*; D006996:Hypocalcemia; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood / Q000378:metabolism*; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D013311:Streptozocin
D001786:Blood Glucose; D010281:Parathyroid Hormone; D013311:Streptozocin; D002118:Calcium