The role of subcellular organelles in hormone secretion : The interactions of calcium, vitamin A, vinblastine, and cytochalasin B in PTH secretion |
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Authors: | B. S. Chertow G. A. Williams Georgiann R. Baker R. D. Surbaugh G. K. Hargis |
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Affiliation: | Departments of Endocrinology and Medicine, VA West Side Hospital and University of Illinois College of Medicine, Chicago, IL 60612, USA |
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Abstract: | To determine the role of subcellular organelles in hormone secretion, we studied the interaction of low calcium concentration (low Ca), retinol (vitamin A, vit A), vinblastine (VB), and cytochalasin B (CB) in parathyroid hormone (PTH) secretion. Bovine parathyroid tissue pieces were incubated in media containing the above agents. Vit A stimulated PTH release to a mean of 170% of control. This effect of vit A was diminished when tissues were simultaneously stimulated with low Ca and, furthermore, absent when tissues were pre-incubated in low Ca.VB had no effect on low Ca-stimulated secretion, but did inhibit vit A-induced secretion in the presence of low Ca.CB stimulated PTH secretion to a mean of 150% of control during the second and third hours of incubation. CB had at least an additive effect with low Ca in stimulating PTH secretion, with a more prompt and greater response than seen in normal calcium. VB did not inhibit the acute effect of CB on secretion in normal calcium media, but did inhibit CB-induced secretion during the third hour of incubation.None of the agents stimulated the release of lysosomal cathepsin D, and vit A and CB did not stimulate the release of LDH.Our results suggest that; (1) vit A and low Ca stimulate PTH secretion through a common pathway involving the cell membrane; (2) CB stimulates PTH secretion through a separate effect on the cell membrane or submembrane microfilaments, which normally retards secretion of PTH; and (3) microtubular proteins may facilitate basal secretion of PTH, but are not involved in low Ca-stimulated secretion of PTH. |
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Keywords: | Address reprint requests to: B. S. Chertow Endocrinology Section (M.P. 172) Va West Side Hospital P.O. Box 8195 Chicago IL 60680 USA. |
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