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S D Silberberg

Publications and source records attributed to S D Silberberg.

21 records · Page 2Linked to original sources
PubMed1989

Endothelin increases single-channel calcium currents in coronary arterial smooth muscle cells.

Endothelin (ET), a newly identified vasoconstrictor peptide produced by endothelial cells, depends on extracellular calcium for its action [(1988) Nature 332, 411-415]. It is not yet known whether the increase in calcium influx induced by ET results from a direct effect on the Ca2+ channels or is secondary to a reduction in membrane potential. To address this question, we studied the effects of ET on single-channel calcium currents of freshly dissociated porcine coronary artery smooth muscle cells using the cell-attached mode of the patch-clamp technique. We show that ET increases Ca2+-channel activity with no effect on channel open time or conductance. The ability of bath-applied ET to increase single-channel calcium currents in the cell-attached mode is evidence that the peptide acts via a second messenger system.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMedDate not supplied

Activation of protein kinase C augments evoked transmitter release.

In view of the emerging role of the phosphoinositide system in cellular communication we examined its involvement in quantal-transmitter release, which is a key element in synaptic transmission. Transmitter release is normally activated by an increase in intracellular calcium, achieved either by entry of calcium ions through the presynaptic membrane or by intracellular calcium liberation. One of the targets of the phosphoinositide signalling system is the enzyme protein kinase C (PKC), which can be activated experimentally by tumour promoting phorbol esters, including 12-O-tetradecanoylphorbol-13-acetate (TPA). Such activation of PKC may be implicated in transmitter release in two ways. First, phorbol esters were found to increase secretion and enhance calcium currents; it might therefore be expected that they would increase synaptic transmitter release. But phorbol esters also inhibit the calcium current in dorsal root ganglion neurones. We report that the phorbol ester TPA augments synaptic transmission at the neuromuscular junction by increasing transmitter liberation. Activation of PKC also depends synaptic depression.

Animals↗