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TPA induces cytoplasmic alkalinization in human monoblastic U-937 cells without activation of Na sup + /H sup + exchange

Journal Article · · Experimental Cell Research; (USA)
The effect of the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) on cytoplasmic pH (pH{sub i}) and H{sup +} extrusion was studied in the human monoblastic cell line U-937. About 2 min after addition of TPA, pH{sub i} started to increase and reached a steady state 10-15 min later. The resulting alkalinization corresponded to 0.03 and 0.09 pH units at 10{sup {minus}10} and 10{sup {minus}7} M TPA, respectively. The TPA-induced increase in pH{sub i} was independent of the presence of extracellular Na{sup +}. Moreover, TPA did not affect the H{sup +} extrusion from the U-937 cells. Together these observations indicate the presence of a novel mechanism for TPA-induced cytoplasmic alkalinization. This mechanism is independent of Na{sup +}/H{sup +} exchange across the plasma membrane, but may involve organelle sequestration of H{sup +}.
OSTI ID:
6794476
Journal Information:
Experimental Cell Research; (USA), Journal Name: Experimental Cell Research; (USA) Vol. 171:1; ISSN ECREA; ISSN 0014-4827
Country of Publication:
United States
Language:
English