Synaptic transmission at high pressure: effects of [Ca2+]o.
1. The effects of pressure on synaptic currents were examined in crayfish abdominal muscles. 2. Helium pressure (10.1 MPa) considerably decreased extracellularly-recorded excitatory junctional potentials associated with increased short-term facilitation. 3. These effects could be mimicked by a reduction of [Ca2+]o, and partially compensated by an increase in [Ca2+]o. 4. Pressure also reduced the amplitude of the extracellular nerve terminal potentials (ENTP) by up to 25%, and significantly increased synaptic delay in a [Ca2+]o-dependent manner. 5. The interaction between compression and various [Ca2+]o were analysed in terms of an existing model of transmitter release. The results were consistent with the hypothesis that high pressure decreases the maximal Ca2+ influx into nerve terminals. 6. The decreased ENTP and increased synaptic delay suggest that additional processes may be involved in pressure effects on synaptic transmission.
Department of Physiology, Corob Center for Medical Research, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
H
H
Golan
Y
Y
Grossman
D000818:Animals; D003400:Astacoidea; D002118:Calcium / Q000502:physiology*; D006371:Helium; D009132:Muscles / Q000294:innervation; D009411:Nerve Endings / Q000502:physiology; D011312:Pressure; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
D006371:Helium; D002118:Calcium