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.
Golan
H
H
Department of Physiology, Corob Center for Medical Research, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Grossman
Y
Y
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