Physiologically active choline esters in certain marine gastropods and other invertebrates

The distribution of 5‐hydroxytryptamine, tetramethylammonium, homarine, and other substances in sea anemones

“…Hydrogen ion modifications for spectrophotometry were obtained by addition of small quantities of HCI or NaOH to blank and sample. Concentrations of homarine were calculated by using the molar extinction coefficient quoted by Keyl, Michaelson & Whittaker (1957).…”

“…As with homarine there was no shift in these values when the pH was adjusted with HC1 or NaOH to pH 2 or 12. The concentrations of homarine were calculated by using the 5-HT, TETRAMETHYLAMMONIUM AND HOMARINE 307 molar extinction coefficient quoted by Keyl et al (1957) and are shown in Table 4. They are, in general, very high, particularly in the tentacles of A. equina and in the coelenteric tissue of C. parasitica, namely 1-5 and 2a 1 mg/g freeze-dried tissue, respectively.…”

The Pharmacological Actions of Some Murexine‐like Substances

“…The main pharmacological properties of murexine (urocanoylcholine, [2-fl-imidazol-4'(59-ylacryloyloxyethyl]trimethylammonium chloride hydrochloride), a naturally occurring neuromuscular blocking agent found in the hypobranchial body of some prosobranchiate molluscs, have been described in previous papers by ourselves (Erspamer and Glasser, 1957) and others Quilliam, 1957;Winbury, 1957;Keyl and Whittaker, 1958).…”

“…Among the other compounds, imidazolebutyrylcholine and imidazolepropoxycholine appeared to be worthy of particular consideration. The relation between the chemical structure of the murexine-like substances studied and their pharmacological effects is discussed.The main pharmacological properties of murexine (urocanoylcholine, [2-fl-imidazol-4'(59-ylacryloyloxyethyl]trimethylammonium chloride hydrochloride), a naturally occurring neuromuscular blocking agent found in the hypobranchial body of some prosobranchiate molluscs, have been described in previous papers by ourselves (Erspamer and Glasser, 1957) and others Quilliam, 1957;Winbury, 1957;Keyl and Whittaker, 1958).The investigations described below are concerned with some pharmacological effects of 19 murexine-like derivatives, synthesized by Pasini, Vercellone, and Erspamer (1956) and by Pasini and Coda (1957 Pharmacological Methods.-The pharmacological methods used in the present investigation were identical with those previously described (Erspamer and Glasser, 1957).Neuromuscular blocking action was tested in the intact animal and on the cat sciatic nerve-gastrocnemius muscle preparation, prepared in the manner described by Burn (1950). The doses required to cause head-drop in 50% of rabbits and to paralyse 50% of dogs were determined after rapid intravenous injection.…”

“…; 8--pyrid-2-ylacryloylcholine showed, at the same dosage, a slight negative chronotropic effect and, occasionally, a slight positive inotropic effect. Keyl, Michaelson, and Whittaker (1957) examined other ring-substituted choline esters and found that, on the frog rectus preparation, indolylacetylcholine manifested the same stimulant effect as murexine, indolylpropionylcholine 60%, and nicotinylcholine 10% of the effect of murexine. Our investigations confirm their statement that /3/-dimethylacryloylcholine has a very strong nicotinic action, in addition to its remarkable muscle-paralysing effect.…”