Electrophysiological properties of pacemaker potentials recorded from myenteric interstitial cells of Cajal (ICC-MY) within the guinea-pig gastric antrum are reviewed briefly. Pacemaker potentials consist of two components, a primary component forming a transient depolarization with a rapidly rising initial phase, followed by a secondary component as a plateau with sustained depolarization. The...

Many signal-transduction processes in higher plant cells have been suggested to be triggered by signal-induced opening of Ca2+ channels in the plasma membrane. However, direct evidence for activation of plasma-membrane Ca2+ channels by physiological signals in higher plants has not yet been obtained. In this context, several lines of evidence suggest that Ca2+ flux into the cytosol of guard cel...

This issue contains five review articles summarizing talks that were presented at a 2-day Physiology and Pathophysiology symposium held in the elegant setting of the National Museum in Cardiff to celebrate the seventieth birthday of Ole Petersen, Chair of the Cardiff School of Biosciences. Ole trained in medicine in Copenhagen and, whilst a student, became fascinated by the physiology of the ex...

1. Gastrin and PACAP stimulate secretion of histamine and pancreastatin from isolated rat stomach ECL cells. We have examined whether or not secretion depends on the free cytosolic Ca2+ concentration ([Ca2+]i) and the pathways by which gastrin and PACAP elevate [Ca2+]i. Secretion was monitored by radioimmunoassay of pancreastatin and changes in [Ca2+]i by video imaging. The patch clamp techniqu...

We have examined the ability of BI (class A) Ca2+ channels, cloned from rabbit brain, to mediate excitation-contraction (E-C) coupling in skeletal muscle. Expression plasmids carrying cDNA encoding BI channels were microinjected into the nuclei of dysgenic mouse myotubes grown in primary culture. Ionic currents and intramembrane charge movements produced by the BI channels were recorded using t...

Previous studies have demonstrated a defect associated with the calcium release mechanism of sarcoplasmic reticulum (SR) from individuals susceptible to malignant hyperthermia (MH). To examine whether SR calcium release channels were indeed altered in MH, SR vesicles were purified from normal and MH susceptible (MHS) porcine muscle. The Ca2+ dependence of calcium efflux rates from 45Ca2(+)-fill...

Hypotonic cell swelling triggers an increase in intracellular Ca2+ concentration that is deemed responsible for the subsequent regulated volume decrease in many cells. To understand the mechanisms underlying this increase, we have studied the Ca2+ sources that contribute to hypotonic cell swelling-induced Ca2+ increase (HICI) in GH3 cells. Fura 2 fluorescence of cell populations revealed that e...

Secretory anterior pituitary cells are of the same origin, but exhibit cell type-specific patterns of spontaneous intracellular Ca2+ signaling and basal hormone secretion. To understand the underlying ionic mechanisms mediating these differences, we compared the ionic channels expressed in somatotrophs, lactotrophs, and gonadotrophs from randomly cycling female rats under identical cell culture...

The channel of the glutamate N-methyl-D-aspartate receptor (NMDAR) transports Ca2+ approximately four times more efficiently than that of Ca2+-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors (AMPAR). To investigate the basis of this difference in these glutamate receptors (GluRs), we measured the ratio of Cs+ efflux and Ca2+ influx in recombinant NMDAR and Ca2+-permeabl...

Canonical transient receptor potential (TRPC) channels are Ca2+-permeable nonselective cation channels that are widely expressed in numerous cell types. Seven different members of TRPC channels have been isolated. The activity of these channels is regulated by the filling state of intracellular Ca2+ stores and/or diacylglycerol and/or Ca2+/calmodulin. However, no evidence is available as to whe...