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Effects of Pressure and Muscle Loading on the Toxic Actions of Echinoderm Saponins in Neuromuscular Tissues
Medical research progress rept. no. 64
NAVAL MEDICAL RESEARCH INST BETHESDA MD
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The toxic marine saponin holothurin A from the Bahamian sea cucumber has been studied with regard to potency in blockade of responses of phrenic nerve-diaphragm PN-D preparations from the rat and the guinea pig under the additional stresses of high environmental pressure or variable loading of the muscle. In the rat tissue, the toxin H- and its desulfated derivative DeH afford a contrast in sensitivity to the effects of elevated pressure a the potency of H- at 1.0 x .0001M is quite high at 14.7 psia, falls sharply as pressure is increased to 130 psia, and then increases moderately as pressure is further raised toward 330 psia b the effect of increased pressure on DeH potency is only marginal. At ambient pressure, the effectiveness of 1.0 x . 0001MH- in depressing twitch responses of rat or guinea pig PN-D preparations is quite high near zero loading of the muscle, and falls to negligible levels as the static loading factor is increased toward 10-20 gg of tissue. These observations are interpreted in terms of a working model for toxin receptors in junctional areas of PN-D tissues. Author
APPROVED FOR PUBLIC RELEASE