ISSN:
1573-5168
Keywords:
tilapia
;
Na/H antiport
;
intracellular pH
;
erythrocytes
;
vasopressin
;
protein kinase C
;
phorbol ester
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The mechanism of modulation of the Na/H antiport was studied in erythrocytes of the tilapia, Oreochromis mossambicus. Activation of the antiport was determined through measurements of variations of intracellular pH, using a pH-sensitive, intracellular fluorescent probe 2′, 7′-bis (carboxyethyl)-5 (6)-carboxyfluorescein (BCECF). Phorbol ester (5 µM), a stimulator of protein kinase C, activated the antiport resulting in an increase of intracellular pH; a maximum of 0.125 ± 0.027 pH units over basal level (mean ± SD; n = 4–6) was reached in 20 min. The effect was blocked by protein kinase C inhibitors staurosporine and H-7, and also by the antiport inhibitor 5-(ethyl-N-isopropyl) amiloride; this demonstrates that the stimulation of the antiport in tilapia erythrocytes can take place through a protein kinase C-mediated mechanism. Vasopressin, an important osmoregulator hormone in teleosts, was able to activate the Na/H antiport, in a manner similar to phorbol ester, but its effect was only partially sensitive to staurosporine inhibition. Considering that the physiological role of the Na/H exchanger in fish is known to be different from its role in mammalian cells, these results indicate that other signal transduction mechanisms can be involved in the modulation of intracellular pH by vasopressin.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1007754925785
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