Na+-H+ antiport during fertilization of the sea urchin egg is blocked by W-7 but is insensitive to K252a and H-7.
Fertilization of the sea urchin egg initiates or accelerates a number of metabolic activities, which have been causally linked to a rise in cytoplasmic pH due to increased Na+-H+ antiport. Two possible regulatory pathways linking sperm-egg fusion to the activity of the antiporter are activation of protein kinase C (PKC) and Ca2+, calmodulin (CaM)-dependent kinase. This report presents the effects of protein kinase inhibitors on antiporter activation during fertilization and treatment with PKC agonists, dioctanoylglycerol or phorbol diester. Protein kinase inhibitors, K252a and H-7 blocked the action of PKC agonists, without inhibiting cytoplasmic alkalinization during fertilization. In contrast, W-7 blocked fertilization-induced rise in cytoplasmic pH, without altering the actions of PKC agonists. These results suggest that the Na+-H+ antiporter may be regulated by PKC or Ca2+, CaM-dependent kinase activities, but activation of the antiporter during fertilization is Ca2+, CaM-dependent, despite production of diacylglycerols by hydrolysis of phosphatidylinositols.
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Department of Zoology, Iowa State University, Ames 50011.
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002227:Carbazoles / Q000494:pharmacology*; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005260:Female; D005306:Fertilization; D026121:Indole Alkaloids; D007546:Isoquinolines / Q000494:pharmacology*; D007700:Kinetics; D010063:Ovum / Q000187:drug effects / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D012617:Sea Urchins; D017923:Sodium-Hydrogen Exchangers; D013449:Sulfonamides / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D002121:Calcium Channel Blockers; D002227:Carbazoles; D002352:Carrier Proteins; D026121:Indole Alkaloids; D007546:Isoquinolines; D010879:Piperazines; D017923:Sodium-Hydrogen Exchangers; D013449:Sulfonamides; C017967:W 7; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C043204:N-(2-guanidinoethyl)-5-isoquinolinesulfonamide; C049985:staurosporine aglycone; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate