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Role of calcium in thyrotrophin-releasing hormone-stimulated release of melanocyte-stimulating hormone from frog neurointermediate lobe.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Lamacz, Marek Tonon, Marie Christine Louiset, Estelle Desrues, Laurence Cazin, Lionel Guy, John Pelletier, Ghislain Vaudry, Hubert |
| Copyright Year | 1988 |
| Abstract | The effect of modifications of extracellular calcium concentrations on alpha-MSH release has been studied using perifused frog neurointermediate lobes. Increasing concentrations of calcium (from 2 to 10 mmol/l) gave rise to a dose-related stimulation of alpha-MSH secretion, whereas reduction of Ca2+ from 2 to 1.5 mmol/l partially inhibited alpha-MSH release. The direct effect of extracellular Ca2+ on alpha-MSH secretion was confirmed by the dose-dependent stimulation of alpha-MSH release induced by the calcium ionophore A23187. Perifusion with a calcium-free medium or blockade of Ca2+ channels by 4 mmol Co2+/l both resulted in an inhibition of spontaneous and TRH-induced alpha-MSH release. Conversely, administration of verapamil or methoxyverapamil (10 mumol/l each) did not alter basal secretion and had no effect on the response of the glands to TRH. Nifedipine (10 mumol/l), which was able to block KCl (20 mmol/l)-evoked alpha-MSH release, induced a slight inhibition of basal alpha-MSH secretion, indicating that extracellular Ca2+ levels may regulate alpha-MSH release in part by Ca2+ influx through voltage-dependent Ca2+ channels. In contrast TRH-induced alpha-MSH release was not affected by nifedipine or dantrolene (10 mumol/l), and BAY-K-8644 (1 mumol/l) did not significantly modify the response of neurointermediate lobes to TRH. Taken together, these results suggest that TRH-induced alpha-MSH secretion is associated with calcium influx across the plasma membrane and that calcium entry caused by TRH may occur through nifedipine/verapamil-insensitive Ca2+ channels. |
| File Format | PDF HTM / HTML |
| DOI | 10.1677/jme.0.0010131 |
| PubMed reference number | 3151249 |
| Journal | Medline |
| Volume Number | 1 |
| Issue Number | 2 |
| Alternate Webpage(s) | https://jme.bioscientifica.com/downloadpdf/journals/jme/1/2/jme_1_2_008.pdf |
| Alternate Webpage(s) | https://doi.org/10.1677/jme.0.0010131 |
| Journal | Journal of molecular endocrinology |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
