Response of Single Nerve Fibers at Different Hydrostatic Pressures

Abstract

The effects of high hydrostatic pressure upon isolated single nerve fibers were investigated. Single nerve fibers were isolated from the nerve innervating the sartorius or semitendinosus muscle of the toad ( Bufo marinus). The responses of single nerve fibers were recorded using the ‘bridge-insulator,’ the ‘interface’ and the ‘three-compartment’ methods. Hydrostatic pressures up to 16,000 psi were developed with a hand operated hydraulic pump. The most striking effect of high pressures was the prolongation of the duration of the response. At 10,000 psi the duration was 4.5–5.0 times the duration at atmospheric pressures. The duration of prolonged responses (by previous tetanization) was not appreciably altered by high pressures. The amplitude, rheobase and shock-response interval were only slightly affected. At 5000 psi the shock-response interval increased by 5–15% and the rheobase by 10–15%.