Spontaneous and evoked activity of motor nerve endings in calcium Ringer

Spontaneous subthreshold activity at motor nerve endings.

Influx of calcium, strontium, and barium in presynaptic nerve endings

Depolarization-induced (potassium-stimulated) influx of 45Ca, 85Sr, and 133Ba was measured in synaptosomes prepared from rat brain. There are two phases of divalent cation entry, "fast" and "slow;" each phase is mediated by channels with distinctive characteristics. The fast channels inactivate (within 1 s) and are blocked by low concentrations (less than 1 micro M) of La. The slow channels do ...

Extra- and intracellular sphingosylphosphorylcholine promote spontaneous transmitter release from frog motor nerve endings.

Similar to phosphatidylinositol bisphosphate, sphingomyelin breakdown generates several lipids, including sphingosylphosphorylcholine (SPC), that are putative signaling molecules. The present study was undertaken to evaluate the involvement of SPC in transmitter release process. Intracellular recordings were made from isolated frog sciatic-sartorius nerve-muscle preparations, and the effects of...

Sodium-evoked, calcium-independent vasopressin release from rat isolated neurohypophysial nerve endings.

1. The effects of Na+ on vasopressin release and on redistribution of Ca2+, Na+ and H+ in isolated rat neurohypophysial nerve endings have been studied. 2. Substituting Na+ for a non-permanent cation produced a pronounced and sustained release of vasopressin. This increase occurred in the absence of external Ca2+ and in nerve endings loaded with the Ca2+ chelator dimethyl-BAPTA (1,2-bis-(O-amin...

Depolarization, intracellular calcium and exocytosis in single vertebrate nerve endings.

We have investigated the temporal relationship between depolarization, elevation of [Ca2+]i and exocytosis in single vertebrate neuroendocrine nerve terminals. The change of [Ca2+]i and vasopressin release were measured with a time resolution of less than 1 s in response to K(+)-induced depolarization. Exocytosis was also monitored in the whole-terminal patch-clamp configuration by time resolve...