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Biomedical subjects

J Elliott

Publications and source records attributed to J Elliott.

At least 253 records · Page 14Linked to original sources
PubMed1980

Investigation of action of enkephalin on the spontaneous and evoked release of acetylcholine from rat cortical and striatal slices.

1 The effects of two synthetic enkephalins, D-Ala2-Met5-enkephalinamide (DALA) and D-Ala2-MePhe4-Met5-(0)-ol-enkephalin (33,824) were tested on the spontaneous and stimulated release of acetylcholine (ACh) from rat cortical and striatal slices. 2 DALA, but not 33,824, caused a modest increase in spontaneous cortical ACh release. Neither enkephalin affected the release of cortical ACh induced by high potassium (25 mM) or veratridine (20 microM). 3 DALA had no effect on the release of ACh from striatal slices occurring spontaneously or in the presence of potassium (25 mM), veratridine (5 microM) or ouabain (10 microM). The enkephalin 33,824 also had no significant action on the striatal ACh release except that it caused a slight enhancement of veratridine-evoked release. 4 It is suggested that enkephalins have no significant action on release of ACh from the cortex or striatum in vitro. Their action on ACh release from the cortex in vivo, seen in previous studies, may be exerted at a subcortical level.

Acetylcholine↗
PubMed1980

Comparative effects of somatostatin and enkephalins on the guinea pig ileum and the rat vas deferens.

The action of somatostatin (SRIF (somatotrophin release inhibiting factor)) was compared with that of Met-enkephalin (Tyr-Gly-Gly-Phe-Met) in the electrically stimulated guinea pig ileum myenteric plexus longitudinal muscle and with that of an enkephalin analogue (FK 33-824 (Tyr-D-Ala-Gly-MePhe-Met-(O)-ol)) in the rat vas deferens. In both tissues SRIF produced a twitch inhibition which was not antagonized by naloxone and which showed a long-lasting tachyphylaxis. The enkephalins tested produced a naloxone-antagonizable inhibition of twitch in both tissues but no tachyphylaxis. Therefore we conclude that SRIF is not acting at opiate receptors in these tissues.

Animals↗
PubMed1979

Interaction of local anesthetics with Torpedo californica membrane-bound acetylcholine receptor.

The effects of local anesthetics on the rate of the agonist-induced increase in ligand affinity of membrane-bound acetylcholine receptor from Torpedo californica were examined. The rate of the transition in receptor affinity was determined by following the time-dependent increase in inhibition of iodinated alpha-bungarotoxin binding caused by 1 microM carbamylcholine. At concentrations below those that directly inhibited the binding of iodinated alpha-bungarotoxin, dibucaine increased the rate of the transition to a high-affinity state and tetracaine decreased this rate. The measured rate constants were 0.026 +/- 0.008 s-1 in the presence and 0.010 +/- 0.002 s-1 in the absence of dibucaine while tetracaine decreased the rate to 0.006 +/- 0.002 s-1 as compared to a control value of 0.012 +/- 0.003 s-1. A parallel was observed between the effectiveness of a compound in increasing or decreasing the rate of the agonist-induced transition in affinity and the change in its apparent inhibition constant in the presence of carbamylcholine (increase or decrease) measured by the displacement of tritiated perhydrohistrionicotoxin. This parallel could be explained by assuming (a) that local anesthetics bound directly to the specific histrionicotoxin binding site or (b) that they bound to a different site and the observed effects were caused by conformational changes.

Acetylcholine↗