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Effect of extracellular ATP on contraction, cytosolic calcium activity, membrane voltage and ion currents of rat mesangial cells in primary culture
Author(s) -
Pavenstädt Hermann,
Gloy Joachim,
Leipziger Jens,
Klär Bettina,
Pfeilschifter Josef,
Schollmeyer Peter,
Greger Rainer
Publication year - 1993
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1993.tb13713.x
Subject(s) - extracellular , depolarization , biophysics , calcium , chemistry , intracellular , membrane potential , contraction (grammar) , biochemistry , biology , endocrinology , organic chemistry
1 The effects of extracellular ATP on contraction, membrane voltage (Vm), ion currents and intracellular calcium activity [Ca 2+ ] i were studied in rat mesangial cells (MC) in primary culture. 2 Addition of extracellular ATP (10 −5 and 10 −4 m ) to MC led to a cell contraction which was independent of extracellular calcium. 3 Membrane voltage (Vm) and ion currents were measured with the nystatin patch clamp technique. ATP induced a concentration‐dependent transient depolarization of Vm (ED 50 : 2 × 10 −6 m ). During the transient depolarization ion currents were monitored simultaneously and showed an increase of the inward‐ and outward current. 4 In a buffer with a reduced extracellular chloride concentration (from 145 to 30 m m ) ATP induced a depolarization augmented to −4 ± 4 mV. 5 ATP‐γ‐S and 2‐methylthio‐ATP depolarized Vm to the same extent as ATP, whereas α,β‐methylene‐ATP (all 10 −5 m ) had no effect on Vm. 6 The Ca 2+ ionophore, A23187, depolarized Vm transiently from −51 ± 2 to −28 ± 4 mV and caused an increase of the inward current. 7 The intracellular calcium activity [Ca 2+ ] i was measured with the fura‐2 technique. ATP stimulated a concentration‐dependent increase of [Ca 2+ ] i (ED 50 : 5 × 10 −6 m ). The increase of [Ca 2+ ] i was biphasic with an initial peak followed by a sustained plateau. 8 The [Ca 2+ ] i peak was still present in an extracellular Ca 2+ ‐free buffer, whereas the plateau was abolished. Verapamil (10 −4 m ) did not inhibit the [Ca 2+ ] i increase induced by ATP. 9 The data indicate that extracellular ATP contracts MC and is able to increase [Ca 2+ ] i by the release of Ca 2+ from intracellular stores and recruitment from the extracellular space. In addition ATP depolarizes Vm of MC by activating a Cl − conductance. The ATP‐induced depolarization is mediated by a P 2y receptor.