Calcium channels have been suggested to play a major role in the initiation of a large number of signal transduction processes in higher plant cells. However, molecular components of higher plant Ca2+ channels remain unidentified to date. Calcium channel blockers of the phenylalkylamine family and bepridil specifically inhibit Ca2+ influx into carrot (Daucus carota L.) cells. By using a phenyla...

The 28 mammalian members of the super-family of transient receptor potential (TRP) channels are cation channels, mostly permeable to both monovalent and divalent cations, and can be subdivided into six main subfamilies: the TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPP (polycystin), TRPML (mucolipin), and the TRPA (ankyrin) groups. TRP channels are widely expressed in a large numb...

In skeletal muscle, dihydropyridine receptors are functionally coupled to ryanodine receptors of the sarcoplasmic reticulum in triadic or diadic junctional complexes. In cardiac muscle direct physical or functional couplings have not been demonstrated. We have tested the hypothesis of functional coupling of L-type Ca2+ channels and ryanodine receptors in rat cardiac myocytes by comparing the ef...

Submembrane [Ca2+]i changes were examined in rat chromaffin cells by monitoring the activity of an endogenous Ca(2+)-dependent protein: the large conductance Ca(2+)-and voltage-activated K+ channel (also known as the BK channel). The Ca2+ and voltage dependence of BK current inactivation and conductance were calibrated first by using defined [Ca2+]i salines. This information was used to examine...

Objective: Several studies have shown the antispasmodic activity of Matricariarecutita without detailing the underlying mechanism(s). The present study was designed to determine whether the antispasmodic mechanisms of M. recutita extract mediated via histaminergic/cholinergic receptors, Ca2+channels, activation of PKA2 and NO release in isolated rabbit jejunum. Methods and Materials: The concen...

The effect of mu-type opioid receptor agonist, D-Ala2,N-MePhe4,Gly5-ol-enkephalin (DAMGO), on high-voltage-activated (HVA) Ca2+ channels in the dissociated rat periaqueductal gray (PAG) neurons was investigated by the use of nystatin-perforated patch recording mode under voltage-clamp condition. Among 188 PAG neurons tested, the HVA Ca2+ channels of 38 neurons (32%) were inhibited by DAMGO (DAM...

An important path of extracellular calcium influx in vascular smooth muscle (VSM) cells is through voltage-activated Ca2+ channels of the plasma membrane. Both high (HVA)- and low (LVA)-voltage-activated Ca2+ currents are present in VSM cells, yet little is known about the relevance of the LVA T-type channels. In this report, we provide molecular evidence for T-type Ca2+ channels in rat arteria...

GABA release from axonal boutons formed by cortical interneurons shows target cell-dependent sensitivity to group III metabotropic glutamate receptor (mGluR) agonists, as well as variable dependence on presynaptic Ca2+ influx via N- and P-type channels. How Ca2+ channels interact with heterogeneous mGluR modulation to determine information flow in the synaptic circuitry is not known. Here we co...

Adenosine 5'-cyclic diphosphoribose [cyclic ADP-ribose (cADPR)], a metabolite of NAD+ that promotes Ca2+ release from sea urchin egg homogenates and microsomal fractions, has been proposed to act as an endogenous agonist of Ca2+ release in sea urchin eggs. We describe experiments showing that a microsomal fraction isolated from Tetrapigus nyger sea urchin eggs displayed Ca2+-selective single ch...

N-type Ca2+ channels bind directly to the synaptic core complex of VAMP/synaptobrevin, syntaxin, and SNAP-25. Peptides containing the synaptic protein interaction ("synprint") site caused dissociation of N-type Ca2+ channels from the synaptic core complex. Introduction of synprint peptides into presynaptic superior cervical ganglion neurons reversibly inhibited synaptic transmission. Fast EPSPs...