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Biomedical subjects

F O Simpson

Publications and source records attributed to F O Simpson.

134 records · Page 8Linked to original sources
PubMed1967

Transverse tubule apertures in mammalian myocardial cells: surface array.

The technique of " freezeetching" tissues for electron microscopy has permitted observation of the external apertures of the transverse tubules. The apertures appear on the cell surface in approximately parallel rows, which can be interpreted as corresponding longitudinally to the spaces between the myofibrils and transversely to the Z regions of the myofibrils.

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PubMedDate not supplied

Cardiovascular effects of prazosin in normotensive and genetically hypertensive rats.

1. The cardiovascular effects of prazosin, a new antihypertensive drug, were studied in normotensive and genetically hypertensive rats. 2. Prazosin, infused intra-arterially, lowered vascular resistance in the blood-perfused rat hind limb. This effect was dependent on the presence of intact sympathetic innervation to the limb; no direct vasodilatation was demonstrated. In this preparation prazosin infusion reduced vasoconstrictor responses to noradrenaline. 3. In the saline-perfused rat mesenteric artery preparation prazosin reduced responses to noradrenaline and sympathetic nerve stimulation but not those to serotonin and vasopressin. Prazosin was more potent than phentolamine, on a molar basis, in reducing the vasoconstrictor effects of noradrenaline. 4. A comparison of the effects of prazosin injected intravenously and into a lateral cerebral ventricle failed to show any central action of the drug on blood pressure. Experiments using the donor blood-perfused, vascularly isolated rat hind limb preparation confirmed that the sympatholytic effect of prazosin occurred within the limb itself.

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