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On the discrepancy between whole‐cell and membrane patch mechanosensitivity in Xenopus oocytes
Author(s) -
Zhang Yong,
Hamill Owen P.
Publication year - 2000
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2000.00101.x
Subject(s) - membrane , biophysics , pipette , xenopus , oocyte , membrane potential , cell membrane , chemistry , piezo1 , vitelline membrane , ion channel , patch clamp , mechanosensitive channels , electrophysiology , materials science , microbiology and biotechnology , biology , biochemistry , embryo , neuroscience , receptor , gene
Mechanical stimulation of voltage‐clamped Xenopus oocytes by inflation, aspiration, or local indentation failed to activate an increase in membrane conductance up to the point of causing visible oocyte damage. The absence of mechanosensitivity is not due to the vitelline membrane, rapid MG channel adaptation or tension‐sensitive recruitment of new membrane. Membrane capacitance measurements indicate that the oocyte surface area is at least 5 times larger than that predicted assuming a smooth sphere. We propose that this excess membrane area provides an immediate reserve that can ‘buffer’ membrane tension changes and thus prevent MG channel activation. High‐resolution images of tightly sealed patches and patch capacitance measurements indicate a smooth membrane that is pulled flat and perpendicular across the inside of the pipette. Brief steps of pressure or suction cause rapid and reversible membrane flexing and MG channel activation. We propose that changes in membrane geometry induced during cell growth and differentiation or as a consequence of specific physiological and pathological conditions may alter mechanosensitivity of a cell independently of the intrinsic properties of channel proteins.