Gerencser G A, Kornette K M
Department of Physiology, College of Medicine, University of Florida, Gainesville 32610, USA.
Comp Biochem Physiol A Mol Integr Physiol. 1998 Feb;119(2):563-7. doi: 10.1016/s1095-6433(97)00467-4.
Na+ absorption by the Aplysia californica foregut is affected through an active Na+ transport mechanism located in the basolateral membrane of the epithelial absorptive cells. Since Cl- absorption by the Aplysia gut has been shown to be very different from that demonstrated in vertebrate gut, the present study was undertaken to discern if Na+ transport was also different from that observed in vertebrate preparations. Utilizing microelectrode technique, it was demonstrated that intracellular K+ activity is above electrochemical equilibrium in the Aplysia absorptive cells and that serosal ouabain, Ba2+ or Cd2+ abolished this asymmetry in K+ electrochemical potential. Neither bumetanide nor furosemide had any effect on intracellular K+ activities, mucosal membrane potentials or transepithelial potentials in the Aplysia gut preparation. These results are consistent with the operation of a basolateral Na+/K+ pump.
加州海兔前肠对Na⁺的吸收是通过位于上皮吸收细胞基底外侧膜的一种主动Na⁺转运机制来实现的。由于已证明海兔肠道对Cl⁻的吸收与脊椎动物肠道的吸收有很大不同，因此进行本研究以确定Na⁺转运是否也与在脊椎动物标本中观察到的不同。利用微电极技术，证明了在海兔吸收细胞中细胞内K⁺活性高于电化学平衡，并且浆膜哇巴因、Ba²⁺或Cd²⁺消除了K⁺电化学势的这种不对称性。布美他尼和呋塞米对海兔肠道标本中的细胞内K⁺活性、黏膜膜电位或跨上皮电位均无任何影响。这些结果与基底外侧Na⁺/K⁺泵的运作一致。
