On the nature and action of coclcntcratc toxins 293 



If the spontaneous autotomies produced by extracts of Mcirii/ium tentacles were, 

 in part, due to the presence of an MciN-likc substance, it might be possible to prevent 

 these autotomies by previous or simultaneous injections of Et4N. Both procedures 

 were followed. A given extract of Metridium tentacles (M-2), when diluted I :l() with 

 sea water, produced 38 spontaneous autotomies of chelae and walking legs, and 

 produced a moderately severe paralysis. When this extract was diluted 1 :10 with I % 

 Et4N, rather than sea water, and 0-05 ml injected, there were no spontaneous autotomies 

 and no signs of paralysis. In another experiment a given dilution of extract induced 

 40 spontaneous autotomies in ten crabs. In a second lot of crabs, 15 minutes after 

 the injection of 0-05 ml of 1 % Et^N, the same dilution of extract produced no auto- 

 tomies. Banthine, a drug used clinically to block acetylcholine action in vertebrate 

 autonomic ganglia (as is Et4N), is a derivative of EtiN. In one experiment 005 ml 

 of 10"^ Banthine completely blocked the autotomy-inducing and paralyzing action of 

 a Metridium extract (M-3, 1 :20) that had produced 50 spontaneous autotomies in a 

 control group of 10 crabs. 



These experiments done at Friday Harbor provided further evidence for the occur- 

 rence of a quaternary ammonium base (MciN derivative) in extracts of coelenterate 

 tentacles. But Me4N alone could not account for all of the observed actions of the 

 extracts on the autotomy reflex of ilea mordax and Hemigrapsus nudus. 



(b) Evidence for an amine in tentacle extracts 



It is a common observation that the sting of Physalia and certain jellyfishes is 

 followed by a painful burning sensation, localized swelling or wheals, redness and 

 urticarial eruptions. Among the more recent descriptions of these and other symptoms, 

 the following may be referred to for further details: Allnutt, 1926; Wade, 1928; 

 Frachtman and McCollum, 1945; McNeill, 1945; Bernstein, 1947. These 

 symptoms are among those that might be expected if histamine were a constituent of 

 nematocyst toxins or if a histamine releaser were present. Accordingly, crabs were 

 injected with histamine. A dose of 0-05 ml of 1 % histamine caused marked paralysis 

 but no spontaneous autotomies. One-tenth this dose caused a mild spastic stiffening 

 of the legs. Pyribenzamine, an antihistamine, was tested. A dose of 0-05 ml o\' I % 

 pyribenzamine caused rapid autotomy of 70% of the chelae but no walking legs were 

 dropped, nor could they be made to autotomize by crushing. One-tenth this dose of 

 pyribenzamine clearly inhibited autotomy of legs and antagonized the autotomizing 

 effect of Metridium tentacle extract. These results further suggest that a histamine-like 

 substance or a histamine releaser may be a constituent of nematocyst toxins. 



(c) Action of extracts on the mollusc heart 



The isolated ventricle of the heart of the quahog, Venus mercenaria, is a sensitive 

 test object for the bioassay of a variety of quaternary ammonium compounds (Welsh 

 and Taub, 1948; 1950; 1951). Me4N and many of its derivatives were known to 

 decrease the amplitude and frequency of heart beat. Some amines, such as adrenaline 

 and tyramine, were known to be excitatory when applied to the isolated I'enus heart. 

 It was decided to test the action of coelenterate tentacle extracts on an isolated mollusc 



heart. 



Exploratory tests of hearts of several molluscs of the Friday Harbor region indicated 



