Intracellular sodium activity in the sea urchin egg during fertilization.
Fertilization of the sea urchin egg triggers a sequence of events that are necessary for metabolic derepression and stimulation of proliferation. Changes in intracellular Ca2+ and H+ activities regulate the sequence of events. Intracellular sodium activity is important in the regulation of the intracellular activities of these ions and may directly regulate metabolic events. Using Na+-sensitive microelectrodes we continuously measured the intracellular Na+ activity during fertilization. The results show an increase in intracellular sodium activity medicated by two pathways of Na+ entry: Na+ permeability increase during the fertilization potential and initiation of Na+-H+ exchange activity. Intracellular Na+ activity returned to unfertilized levels by 20 min after fertilization. This decrease was inhibited by ouabain, which suggests the activation of Na+, K+ ATPase during fertilization.
S S
SS
Shen
L J
LJ
Burgart
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D005260:Female; D005306:Fertilization / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007424:Intracellular Fluid / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D010063:Ovum / Q000378:metabolism* / Q000502:physiology; D012617:Sea Urchins / Q000378:metabolism*; D012623:Seawater; D012964:Sodium / Q000378:metabolism*
D007473:Ion Channels; D010042:Ouabain; D000584:Amiloride; D012964:Sodium