Ryanodine receptors (RyRs) are highly conductive intracellular Ca(2+) release channels which are widely expressed in the CNS. They rapidly increase the intracellular Ca(2+) concentrations in neuronal cells in response to Ca(2+) influx through voltage-gated Ca(2+) channels. A previous study reported that RyRs were expressed in thalamocortical (TC) neurons, but their physiological function has re...

Loading slices of rat barrel cortex with 50 microM BAPTA-AM while recording from pyramidal cells in layer II induces a marked reduction in both the frequency and amplitudes of mEPSCs. These changes are due to a presynaptic action. Blocking the refilling of Ca(2+) stores with 20 microM cyclopiazonic acid (CPA), a SERCA pump inhibitor, in conjunction with neuronal depolarisation to activate Ca(2+...

The effects of external pH (7.0-8.0) on intracellular Ca(2+) signals (Ca(2+) sparks and Ca(2+) waves) were examined in smooth muscle cells from intact pressurized arteries from rats. Elevating the external pH from 7.4 to 7.5 increased the frequency of local, Ca(2+) transients, or "Ca(2+) sparks," and, at pH 7.6, significantly increased the frequency of Ca(2+) waves. Alkaline pH-induced Ca(2+) w...

Caffeine has been much used to examine the possibility that ryanodine receptors similar to those found in skeletal and cardiac muscle may be more widely distributed and perhaps contribute to regenerative Ca2+ signals in electrically inexcitable cells. In permeabilized hepatocytes loaded with 45Ca2+, caffeine (> or = 5 mM) decreased the 45Ca2+ content of the intracellular stores by up to 60%; th...

he role of cyclic ADP-ribose in the amplification of subcellular and global Ca 2 signaling upon stimulation of P2Y purinergic receptors was studied in 3T3 fibroblasts. Either (1) 3T3 fibroblasts (CD38 cells), (2) 3T3 fibroblasts preloaded by incubation with extracellular cyclic ADP-ribose (cADPR), (3) 3T3 fibroblasts microinjected with ryanodine, or (4) 3T3 fibroblasts transfected to express th...

Heppner, Thomas J., Adrian D. Bonev, L. Fernando Santana, and Mark T. Nelson. Alkaline pH shifts Ca2 sparks to Ca2 waves in smooth muscle cells of pressurized cerebral arteries. Am J Physiol Heart Circ Physiol 283: H2169–H2176, 2002; 10.1152/ajpheart.00603.2002.—The effects of external pH (7.0–8.0) on intracellular Ca2 signals (Ca2 sparks and Ca2 waves) were examined in smooth muscle cells from...

The mechanism of action of tonically applied choline, the agonist of α7 nicotinic acetylcholine receptors (nAChRs), to the spontaneous and evoked release of a neurotransmitter in mouse motor synapses in diaphragm neuromuscular preparations using intracellular microelectrode recordings of miniature endplate potentials (MEPPs) and evoked endplate potentials (EPPs) was studied. Exogenous choline w...

Previous studies of arterial smooth muscle have shown that inositol 1,4,5-trisphosphate (IP3) and cyclic ADP-ribose mobilize Ca2+ from the sarcoplasmic reticulum. In contrast, little is known about Ca2+ mobilization by nicotinic acid adenine dinucleotide phosphate, a pyridine nucleotide derived from beta-NADP+. We show here that intracellular dialysis of nicotinic acid adenine dinucleotide phos...