Fig. 5. Blockage of pHi increase of oocytes in the ovary of stimulated animals. (A) Ovaries were isolated from the stimulated animals 15 minutes before measurement of fluorescence ratios. They were immersed in zero-Na⁺ artificial SW and dissociated oocytes were obtained. Oocytes were continuously treated with zero-Na⁺ artificial SW for 15 minutes, during which time they were microinjected with BCECF. The zero-Na⁺ artificial SW was replaced by normal SW 60 minutes or 180 minutes after injection of 1-MA into the body cavity of the animal, followed by measurement of fluorescence ratios. (B) Ovaries were isolated from non-stimulated animals and immersed in zero-Na⁺ artificial SW. Then, oocytes in the ovaries were isolated and microinjected with BCECF. The zero-Na⁺ artificial SW was replaced by normal SW at 10 minutes, and again replaced by zero-Na⁺ artificial SW at 60 minutes. A small rise of pHi occurred when the zero-Na⁺ artificial SW was replaced by normal SW. (C) The pHi increase of oocytes from non-stimulated animals was induced by 1-MA in normal SW, which was replaced by zero-Na⁺ artificial SW without 1-MA at 65 minutes, and again replaced by normal SW at 93 minutes. High pHi induced by normal SW containing 1-MA was not affected by zero-Na⁺ artificial SW. (D) Ovaries were isolated from the stimulated animals and immersed in normal SW. Immediately, oocytes in the ovaries were isolated and microinjected with BCECF, and the pHi of oocytes was measured. pHi increased with time after removal of the ovary from the animal.