Search PubMed⌕ Search

Biomedical subjects

G Henderson

Publications and source records attributed to G Henderson.

At least 145 records · Page 8Linked to original sources
PubMed1976

The effects of morphine on the release of noradrenaline from the mouse vas deferens.

Electrical field stimulation of the mouse vas deferens (TO and C57/BL strains) caused the release of noradrenaline into the bathing medium. 2 Phenoxybenzamine (30 muM) or phentolamine (36 muM) plus cocaine (13 muM) caused a considerable increase in the noradrenaline output. 3 In the vasa deferentia from TO mice the output per pulse of noradrenaline was constant at frequencies of stimulation from 0.5 to 15 Hz whereas in the vasa deferentia from C57/BL mice the output per pulse of noradrenaline increased two-fold from 1.5 to 15 Hz. 4 Morphine (2 muM) inhibited the contractions of the vasa deferentia from TO mice. This effect was greater at low (0.1-1 Hz) than at high (10 Hz) frequencies of stimulation. Morphine (2 muM) did not inhibit the response of the tissue to exogenous noradrenaline. 5 Morphine (1 muM) reduced the noradrenaline output from the vasa deferentia of TO mice stimulated at 1.5 Hz but did not reduce the noradrenaline output at 15 Hz. At 1.5 Hz the reduction of noradrenaline output was reversed by naloxone (0.05 muM). 6 Morphine (5 muM) did not inhibit the uptake of [3H]-noradrenaline into the vasa deferentia from TO mice. 7 Only in high concentrations (ID50 30.88 muM) did morphine inhibit the contractions of the vasa deferentia from C57/BL mice. 8 Normorphine (100 muM) did not reduce the noradrenaline output from vasa deferentia of C57/BL mice.

Animals↗
PubMed1976

Depression by morphine of excitatory junction potentials in the vas deferens of the mouse.

1 Intracellular recordings were made from smooth muscle cells of the mouse vas deferens. Excitatory junction potentials (e.j.ps) were evoked by stimulation of the intramural nerves. 2 Normorphine (50 nM-5muM) depressed the amplitude of the e.j.p. The ED50 was 430 nM. The latency of the e.j.p. and the resting membrane potential of the smooth muscle cells were unaffected by normorphine. 3 The depression of the e.j.p. by narcotic analgesic drugs was stereospecific. 4 Naloxone (100 nM) completely reversed the depression of the e.j.p. produced by normorphine (1 muM). Naloxone (100 nM) alone did not alter the amplitude of the e.j.p. 5 Normorphine (1 muM) did not prevent the depolarization of the smooth muscle cells produced by exogenous noradrenaline (10 muM). 6 It is concluded that narcotic analgesic drugs act directly upon the transmitter release sites to reduce the amount of noradrenaline liberated by each nerve impulse.

Animals↗
PubMed1975

Cell counts in the human cerebral cortex using a traditional and an automatic method.

This study compares the results of cell counting in the human cerebral cortex by a traditional and an automatic procedure. Four blocks were taken from standard areas of each of 10 brains from individuals aged 18-95 years and showing no neurological abnormality. Sections from each block were counted by traditional and automatic methods, both of which are described. The traditional method used photomicrographs and the automatic procedure used the quantimet 720 Image Analysing Computer. The degree of reproducibility of each method was measured and the results are discussed and tabulated. Comparison are made of the total cell counts, and the counts of cells measuring greater than 20 um across. The results show a high level of correlation between the two procedures but the manual count yields higher number for total cells and smaller numbers for large cells than the automatic method. The reasons for these discrepancies are discussed and examples of the arterfacts which produce them are giver. Using the traditional method described the amount of meterial examined took about 4 months to study. The sane tissue can be assessed in 1 day using the automatic apparatus. The high speed and close correlation achieved by the automatic procedure makes it a valuable aid in quantitative cell studies in the central nervous system.

Cell Count↗
PubMed1975

The effects of morphine on the release of noradrenaline from the cat isolated nictitating membrane and the guinea-pig ileum myenteric plexus-longitudinal muscle preparation.

1. Electrical field stimulation of either the cat isolated nictitating membrane or the guinea-pig ileum myenteric plexus-longitudinal muscle preparation caused the release of noradrenaline into the bathing medium. 2. In the cat nictitating membrane, the output per pulse of noradrenaline was constant at frequencies of stimulation from 0.5 to 15 Hz. In the guinea-pig myenteric plexus preparation the output per pulse of noradrenaline increased as the frequency of stimulation was increased from 2 to 16 Hz. 3. Phenoxybenzamine (29.3 muM) caused a marked increase in the noradrenaline output from both the cat nictitating membrane and guinea-pig myenteric plexus preparations. 4. Morphine (0.13-8 muM) inhibited the contractions of the cat nictitating membrane caused by electrical stimulation. This effect was greater at low (1Hz) than at high (15Hz) frequencies of stimulat The site of action is at the nerve-smooth muscle junction. 5. The action of narcotic analgesic drugs on the cat nictitating membrane showed stereospecificity. Naloxone (0.1 muM) reversed the inhibition caused by normorphine (3.2 muM). 6. Morphine (3 muM) reduced the noradrenaline output from the cat nictitating membrane stimulated at 1 Hz but not at 15 Hz. At 1 Hz, the inhibition of noradrenaline output by normorphine (muM) was reversed by naloxone (0.25 muM). 7. Morphine (1.5 muM) did not alter the noradrenaline output from the guinea-pig myenteric plexus preparation stimulated at 2 or 16 Hz.

Animals↗
PubMed1973

Longitudinal fibre splitting in muscular dystrophy: a serial cinematographic study.

A technique of block surface-staining and serial cinematography was modified to review serial sections of normal and dystrophic muscle from the Bar Harbor 129 Re strain of mice as a preliminary study of fibre splitting in dystrophic muscle. Using this technique, muscle fibres were reconstructed for up to 1·5 mm of their length without difficulty. Split fibres were identified only when the actual separation of fibres was observed. Splitting was seen to be a significant cause of the variations in fibre diameter and was at times responsible for the formation of groups of small atrophic fibres which resembled those seen in denervation atrophy. Complex multiple splitting and recombination of daughter and parent fibres was also observed and reconstructed to scale. These results may have considerable significance for the interpretation of physiological data on both human and murine dystrophic muscle.

Animals↗
PubMed1972

A new example of a morphine-sensitive neuro-effector junction: adrenergic transmission in the mouse vas deferens.

The isolated mouse vas deferens possesses an adrenergic excitatory motor innervation which can be inhibited by low concentrations of morphine (ID50=0.5 muM). This effect of morphine is mediated by specific receptors which are blocked by naloxone. Activation of the morphine receptors inhibits noradrenaline release. It is concluded that adrenergic neurotransmission in the mouse vas deferens differs in some important way from that at the more common, morphine-insensitive, adrenergic junctions.

Animals↗
PubMed1969

Regulated enzymes of aromatic amino acid synthesis: control, isozymic nature, and aggregation in Bacillus subtilis and Bacillus licheniformis.

Several regulated enzymes involved in aromatic amino acid synthesis were studied in Bacillus subtilis and B. licheniformis with reference to organization and control mechanisms. B. subtilis has been previously shown (23) to have a single 3-deoxy-d-arabinoheptulosonate 7-phosphate (DAHP) synthetase but to have two isozymic forms of both chorismate mutase and shikimate kinase. Extracts of B. licheniformis chromatographed on diethylaminoethyl (DEAE) cellulose indicated a single DAHP synthetase and two isozymic forms of chorismate mutase, but only a single shikimate kinase activity. The evidence for isozymes has been supported by the inability to find strains mutant in these activities, although strains mutant for the other activities were readily obtained. DAHP synthetase, one of the isozymes of chorismate mutase, and one of the isozymes of shikimate kinase were found in a single complex in B. subtilis. No such complex could be detected in B. licheniformis. DAHP synthetase and shikimate kinase from B. subtilis were feedback-inhibited by chorismate and prephenate. DAHP synthetase from B. licheniformis was also feedback-inhibited by these two intermediates, but shikimate kinase was inhibited only by chorismate. When the cells were grown in limiting tyrosine, the DAHP synthetase, chorismate mutase, and shikimate kinase activities of B. subtilis were derepressed in parallel, but only DAHP synthetase and chorismate mutase were derepressible in B. licheniformis. Implications of the differences as well as the similarities between the control and the pattern of enzyme aggregation in the two related species of bacilli were discussed.

Bacillus↗
PubMed1968

A new route to the imidazole-2-thiones from 2-thiohydantoins. Implications in the study of ergothioneine.

1. 2-Thiohydantoins are reduced by borohydrides to 4(5)-hydroxyimidazolidine-2-thiones, which eliminate water in acid to form imidazole-2-thiones. Both steps take place in mild conditions, in high yield. A number of imidazole-2-thiones have been synthesized by this sequence of steps, with one, two or three substituents in the 1-, 3- and 4(5)-positions. 2. 4(5)-Hydroxyimidazolidine-2-thiones are ammonium pseudo-bases, giving rise to an equilibrium mixture of amino aldehyde, carbinolamine and mesomeric ammonium cationic forms. The elimination of water is suggested to be a property of the mesomeric ammonium cation. 3. The mild conditions in which imidazole-2-thiones are formed from 4(5)-hydroxyimidazolidine-2-thiones are similar to those in which ergothioneine, a naturally occurring imidazole-2-thione of uncertain function, is normally released and measured. It is suggested that the occurrence in vivo of a precursor to ergothioneine, in the form of a 4(5)-hydroxyimidazolidine-2-thione, would explain many otherwise conflicting published data.

Aldehydes↗