Effects of short-term treatment with calcium on the parathyroid gland of the rat, under particular consideration of the alteration of storage granules.
Short-term effects of CaCl2-treatment on parathyroid cells of the rat, especially on their storage granules, were studied at the ultrastructural level. After an injection of 4% CaCl2, serum calcium levels (SCL) rapidly increased from 9.1 mg/dl (controls) to a maximum of 14.9 mg/dl at 20 min. At 5 min after the injection, the number of type-I storage granules (large core) [NSG-I] and that of type-II storage granules (small core) [NSG-II] remained unchanged, in spite of elevated SCL (12.4 mg/dl). As soon as SCL rose to 13.2 mg/dl at 7.5 min, NSG-I gradually decreased to a minimum at 30 min; in contrast, NSG-II gradually increased to a maximum at 30 min. Vacuolar bodies also increased together with the augmentation of type-II storage granules. The average diameter of the core of the storage granules decreased significantly after the injection. Protein A-gold method for immunocytochemistry showed that the cores of these granules contain parathormone. Acid-phosphatase activity was occasionally found in storage granules of both types, especially in those of type II. It is concluded that type-I storage granules may be transformed into vacuolar bodies via type-II granules as a result of hydrolysis, and that these processes may be accelerated during hypercalcemia.
D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D002122:Calcium Chloride / Q000494:pharmacology*; D003594:Cytoplasmic Granules / Q000187:drug effects* / Q000648:ultrastructure; D006651:Histocytochemistry; D007120:Immunochemistry; D008297:Male; D010280:Parathyroid Glands / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D000135:Acid Phosphatase; D002122:Calcium Chloride