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M Morton

Publications and source records attributed to M Morton.

11 recordsLinked to original sources
PubMed1992

Tetrodotoxin-insensitive sodium channels in a cardiac cell line from a transgenic mouse.

The electrophysiological properties of a cardiac cell line (MCM1) originating from a transgenic mouse were characterized. The dominant current in these cells is a sodium current that is insensitive to concentrations of tetrodotoxin (TTX) up to 100 microM. It activates and inactivates rapidly with half-maximal activation at -40 mV and half-maximal inactivation at -79 mV. This sodium current is reduced by agents that increase intracellular adenosine 3',5'-cyclic monophosphate (cAMP) and activate cAMP-dependent protein kinase including isoproterenol, 8-bromo-cAMP, and isobutylmethylxanthine. The phenylalkylamine desmethoxyverapamil blocks the TTX-insensitive sodium current in MCM1 cells in both tonic and use-dependent fashion. Membrane depolarization enhances this block. It is proposed that the TTX-insensitive sodium current in these cells may be similar in origin to the embryonic type of TTX-insensitive sodium current described in other cardiac and skeletal muscle preparations.

1-Methyl-3-isobutylxanthine↗
PubMed1977

Mortality and the concentration of elements in tap water in county boroughs in England and Wales.

To explain the associations of water hardness and air temperature with area differences in ischaemic heart disease mortality, samples of tap water were obtained from homes in 61 county boroughs in England and Wales, and the concentration of calcium and 12 other elements was estimated. Multiple regressions were calculated with the death rates from various causes as dependent variables and with the concentration of the elements in the tap water, mean annual temperature, mean annual rainfall, and a socioeconomic index as independent variables. The well known negative association between water hardness and ischaemic heart disease was shown to be due to calcium, and none of 12 other elements examined appeared to contribute significantly to the association. Area differences in other causes of death also showed an association with calcium. There was little association between temperature and ischaemic heart disease.

Adult↗
PubMed1977

Pulmonary tissue concentrations of ethchlorvynol after intravenous injection.

Noncardiogenic pulmonary edema has been reported to follow the intravenous use of ethchlorvynol (Placidyl) in both human clinical and animal experimental situations. In a further attempt to define ethchlorvynol-pulmonary tissue inter-relations, we measured ethchlorvynol concentrations in venous and arterial blood and lung and liver tissue of dogs after intravenous injection of 15 to 25 mg of the drug per kg of body weight. In 10 dogs, the mean +/- SEM lung concentrations 1, 3, and 5 min after injection were 70 +/- 20, 50 +/- 13, and 24 +/- 9 mug per g of tissue, respectively. Simultaneous mean +/- SEM venous contrations were 75 +/- 40, 29+/-5, and 22 +/- 5 mug per ml of blood, respectively. During minutes 1 and 3, the liver concentrations were lower than those found in the lung. In an additional 3 dogs, injection of ethchlorvynol into the portal vein led to higher concentrations (at all sample times) in the liver when compared to the lung. In vitro lung slice studies using ethchlorvynol labeled with iodine-131 revealed no active energy-dependent uptake. Intravenously administered ethchlorvynol rapidly fluxes into and out of lung tissue, apparently following the laws of diffusion.

Animals↗
PubMed1976

Musculoskeletal management of the severely burned child.

Aggressive management of severe burns minimizes contractures and helps to maintain muscle tone, joint function and psychological well-being. The positioning, activity and exercise programs, splinting and bandaging, and skin care of burned children carried out by the burns team at the Hospital for Sick Children, Toronto is outlined.

Burns↗