HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Thorn, P Search for Related Content PubMed PubMed Citation Articles by Thorn, P

Babraham Institute, Cambridge, UK.

1. Histamine-stimulated [Ca2+]i oscillations were studied in > 162 HeLa cells using the techniques of Ca2+ imaging, patch clamp and single-cell indo-1 fluorescence. 2. [Ca2+]i oscillations in HeLa cells were acutely dependent on extracellular Ca2+ and were also blocked by the extracellular addition of Cd2+ (100 microM). The Mn2+ quench technique, using fura-2 fluorescence, demonstrated that agonist-stimulated Ca2+ oscillations were associated with an increase in plasma membrane Mn2+ permeability. However, no cyclic fluctuations in Mn2+ influx were resolved over the period of [Ca2+]i spiking. 3. In whole-cell patch clamped cells an imposed potential of +80 mV was shown to block the thapsigargin-induced Ca2+ influx. Histamine and Ins(2,4,5)P3-induced [Ca2+]i oscillations were tested for the phase dependence on extracellular Ca2+ by rapidly switching the membrane potential to +80 mV, reversibly blocking Ca2+ influx. Ca2+ spikes were abolished by steps to +80 mV made at the point of spike initiation but not by steps made after development of the rapid rising phase of the spike. Steps of membrane potential to +80 mV, for increasing periods of time during the interspike period, increased the latency to the next [Ca2+]i spike by up to a maximum of approximately 150% of the control interspike interval. 4. It is concluded that the extracellular Ca2+ dependence of the histamine-induced [Ca2+]i oscillations is due to a crucial role of Ca2+ influx during spike initiation and an additional important role in setting the interspike interval. The results obtained can be interpreted in terms of a constant stimulated Ca2+ influx during [Ca2+]i spiking.

This article has been cited by other articles:

				S. P. Parsons and T. B. Bolton Localised calcium release events in cells from the muscle of guinea-pig gastric fundus J. Physiol., February 1, 2004; 554(3): 687 - 705. [Abstract] [Full Text] [PDF]