Browsing by Author "Isaacson, Leon"

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    An electrophysiological study of ion transport across the isolated perfused malpighian tubule of Onymacris plana
    (1993) Fisher, David Willis; Isaacson, Leon
    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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    Non-selective, calcium-permeable channels in the apical membrane of rabbit renal tubules and in the basolateral membrane of human renal tubules : an exploratory patch clamp study
    (1992) Saunders, James; Isaacson, Leon
    The presence of calcium (Ca) channels has been investigated in the apical membrane of various segments of rabbit renal tubules and in the basolateral membrane of human tubules, using the patch clamp technique. The rabbit tubule segments comprised proximal straight tubules (PST), thick ascending limbs (TAL), distal convoluted tubules (OCT), and cortical collecting ducts (CCD). The human tubule segments could not be identified, but were probably of proximal origin. The luminal surfaces of the individual tubule segments were accessed by perfusing the tubule and inserting the patch pipette through the open end or, more frequently, by tearing open the tubule to allow direct access by a patch electrode. Either Ba (90 mM) or Ca (70 mM) was used in the pipettes. Where possible, channel activity was sought in voltage clamped (30 to -60 m V) excised patches. The data were digitized at l kHz, and filtered (200- 500 Hz) by a six-pole Bessel filter.
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    Quantitative cytochemical studies of acid secretagogue effects on the carbonic anhydrase activity of gastric parietal cell sections
    (1982) Klaff, Leslie Joseph; Vinik, Aaron I; Jackson, W P U; Isaacson, Leon
    This thesis presents work designed to study the effects of acid secretagogues upon the parietal cell, in order to gain a greater understanding of their modes of action, and interaction and the role of circulating secretagogues in the mediation of parietal cell function, with the aim of increasing the understanding of the pathophysiology of the world-wide problem of peptic ulcer disease.