Influence of thyroid status on Ca2+ mobilization and amylase secretion in rat pancreatic acini.
Thyroid hormones influence Ca2+ homeostasis in both skeletal and cardiac muscle. Since secretory cells, like muscle cells, store and use Ca2+ in stimulus-response coupling, we have studied the effects of thyroid status on Ca2+ mobilization and secretion in a model secretory tissue, the pancreatic acinar cell. Hyperthyroidism was induced by rats by daily, subcutaneous injections of triiodothyronine for 8 days and hypothyroidism by adding 6-n-propyl-2-thiouracil to the drinking water for 14 days. Pancreatic acini were prepared by collagenase digestion of pancreatic tissue from hyper- and hypo-thyroid animals and from euthyroid controls. Ca2(+)-mobilization was assessed using Quin-2 fluorescence and secretion by assaying amylase release. The data indicate that the amount of Ca2+ mobilized by the muscarinic agonist carbachol or by cholecystokinin octapeptide increases with increasing thyroid hormone concentrations. Only in hypothyroidism was this change in Ca2+ homeostasis reflected by a parallel change in amylase secretion. This implies the existence of some compensatory mechanism which stabilizes secretory rate in the face of stimulus-evoked increases in intracellular Ca2+ concentration.
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Department of Physiological Sciences, University of Manchester, UK.
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D000634:Aminoquinolines; D000681:Amylases / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D005456:Fluorescent Dyes; D006706:Homeostasis; D006980:Hyperthyroidism / Q000139:chemically induced / Q000378:metabolism*; D007037:Hypothyroidism / Q000139:chemically induced / Q000378:metabolism*; D015759:Ionomycin / Q000494:pharmacology; D008297:Male; D010179:Pancreas / Q000378:metabolism*; D011441:Propylthiouracil; D051381:Rats; D011919:Rats, Inbred Strains; D012844:Sincalide / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014284:Triiodothyronine
D000634:Aminoquinolines; D005456:Fluorescent Dyes; D014284:Triiodothyronine; D015759:Ionomycin; D011441:Propylthiouracil; D002217:Carbachol; D000681:Amylases; D012844:Sincalide; D013755:Tetradecanoylphorbol Acetate; C035739:Quin2; D002118:Calcium