Effects of depolarizing concentrations of K+ and reduced osmotic pressure on 45Ca2+ accumulation by the rostral pars distalis of the tilapia (Oreochromis mossambicus)
| Autor: | Lisa M.H. Helms, Ian M. Cooke, Peter K.T. Pang, Carol-Ann Ford, E. Gordon Grau, N.Harold Richman, Christine G. Benishin |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
endocrine system
medicine.medical_specialty Oreochromis mossambicus food.ingredient chemistry.chemical_element Calcium In Vitro Techniques Endocrinology food Osmotic Pressure Pituitary Gland Anterior Internal medicine Extracellular medicine Osmotic pressure Animals Osmotic concentration biology Fishes Depolarization Tilapia biology.organism_classification Prolactin chemistry Potassium Animal Science and Zoology hormones hormone substitutes and hormone antagonists |
| Zdroj: | General and comparative endocrinology. 77(2) |
| ISSN: | 0016-6480 |
| Popis: | The accumulation of 45Ca2+ into tilapia prolactin (PRL) tissue was examined under conditions which alter prolactin release. In initial experiments, PRL tissue was incubated in medium containing 12 microCi/ml 45Ca2+ in hyperosmotic medium (355 mOsmolal). Under these conditions, 45Ca2+ accumulated steadily, reaching a plateau within 15-20 min. Subsequent exposure to La3+, which displaces Ca2+ from superficial pools in a wide variety of tissues, rapidly (within 5 min) removed nearly 70% of the 45Ca2+ associated with the tissue. Following this initial removal of 45Ca2+, the level of 45Ca2+ in the PRL tissue remained constant, and is referred to as the La3(+)-resistant pool of Ca2+. This pool of Ca2+ is thought to reflect the entry rate of Ca2+ from extracellular sources. Prolactin tissue exposed to hyposmotic medium or to depolarizing [K+], which stimulates PRL release, significantly increased 45Ca2+ accumulation in this La3(+)-resistant pool. These results indicate that reduced osmotic pressure and depolarization may alter release from tilapia PRL cells, in part, through their ability to increase the entry of extracellular Ca2+. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|