An electrophysiological study of ion transport across the isolated perfused malpighian tubule of Onymacris plana
A knowledge of the ionic and electrical gradients across the Malpighian tubules of Onymacris plana is fundamental to the understanding of the transport mechanisms of fluid across the basolateral and apical membranes. Until now no one has investigated the isolated perfused Malpighian tubule of Onymacris plana and simultaneously measured basolateral potentials. Malpighian tubule segments (about lmm length) were dissected out and perfused in vitro according to the method of Burg et. al. (1966), while the basolateral membrane potential (Vbl) was measured by means of an intracellular microelectrode. Using cable analysis, the effects of DNP, chloride free Ringers, BaCl² (a K⁺-channel blocker), low (25 mM) and high (130 mM) pntassium Ringers (bathing medium), cyclic-AMP and a corpora cardiaca homogenate (CCH) on. the transepithelial resistance and the fractional resistances of the basolateral and apical membranes were investigated.
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