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THE INFLUENCE OF PARATHYROID HORMONE ON THE SECRETION OF PHOSPHATE BY THE PAROTID SALIVARY GLAND OF SHEEP
Author(s) -
Tomas F. M.
Publication year - 1974
Publication title -
quarterly journal of experimental physiology and cognate medical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0033-5541
DOI - 10.1113/expphysiol.1974.sp002274
Subject(s) - parathyroid hormone , endocrinology , medicine , hormone , parotid gland , parathyroid gland , bicarbonate , salivary gland , chemistry , phosphate , secretion rate , calcium , secretion , biology , biochemistry , pathology
The effect of parathyroid hormone on phosphate secretion by the parotid salivary gland in sheep has been examined in three separate studies: the first, with 3 sheep, used free‐flow salivary collection under anaesthesia and intravenous infusion of hormone; the second involved 4 sheep in which ‘stop‐flow’ techniques were applied to one parotid gland; the third was carried out using 6 sheep in which the blood vessels to one parotid gland were isolated and hormone infused at graded rates directly into the arterial supply to the gland. Parathyroid hormone infusion caused an increase in parotid salivary phosphate concentration and secretion rate in all experiments. The response was rapid (within 2–4 min) and also declined rapidly following cessation of infusion. During hormone administration the ratio of salivary to plasma phosphate concentrations for stopped‐flow samples was significantly higher than for controls (22·0 ± 2·1 (S.E.M.) vs 16·0 ± 2·2). Hormone infusion into the blood supply of the isolated parotid gland at rates estimated to give rise to plasma parathyroid hormone levels of about 5, 10 or 20 ng/ml. caused salivary phosphate concentration to rise by 11·6, 19·6 and 25·7 m‐mole/litre respectively. The increment, whether expressed as a percentage or on an absolute basis, was directly related to the dose rate. Parathyroid hormone infusion also altered the secretion of sodium, potassium and bicarbonate, but not of calcium or magnesium. These changes, and those of phosphate, are discussed in relation to the mode of action of parathyroid hormone.