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Biomedical subjects

R G Hart

Publications and source records attributed to R G Hart.

At least 145 records · Page 8Linked to original sources
PubMed1977

The spermatozoon.

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Adenine Nucleotides↗
PubMed1975

Altered ion transport in aortic smooth muscle during deoxycorticosterone acetate hypertension in the rat.

Change in aortic water and electrolyte distribution and in ion turnover were studied during the development of deoxycorticosterone acetate (DOCA) hypertension in the rat. Treatment with DOCA plus saline during the prehypertensive phase was associated with increases in 42K turnover (0.0142 +/- 0.0005 vs. 0.0102 +/- 0.0003 min-1), cell water (0.89 +/- 0.03 vs 0.76 +/- 0.02 kg/kg dry weight), and the ratio of weight to length. These parameters were further increased during the development of hypertension. Significant increases were also observed in total K, Ca, and Mg contents and in Na and C1 contents corrected for the extracellular space. The turnover of 36Cl was increased (0.230 +/- 0.006 vs. 0.136 +/- 0.004 min-1) in DOCA hypertensive rats as was the content of slowly exchanging Cl. Removal of extracellular Ca greatly increased the steady-state turnover of 42K. For control rats, a Ca concentration of 0.1 mM reduced the rate of 42K turnover to less than 50% of the Ca-free value (0.063 +/- 0.004 min-1), whereas DOCA hypertensive rats exhibited only a 10% reduction. At the highest Ca concentration, 5 mM, the 42K turnover was greater in DOCA-treated rats with the hypertensives operating at 67% of maximum efflux or about twice the efflux in controls. It is concluded that significant alterations in ion transport by vascular smooth muscle occur before and during the development of hypertension induced by treatment with DOCA plus saline. Such changes may result from a reduced ability of Ca to stabilize the membrane. It is proposed that such alterations contribute to the changes in vascular reactivity and the hypertrophy associated with hypertension.

Animals↗
PubMed1970

Polytropic montage: ribosomes examined in a tissue section.

Electron micrographs of a variably titled specimen can be blended by computer to form an image of any selected specimen plane. Thus, one can examine a tissue section layer by layer with an effective depth of focus less than 30 A. Ribosomes so observed in rat liver have some resemblances to isolated, tungsten-shadowed particles.

Animals↗
PubMed1968

Electron microscopy of unstained biological material: the polytropic montage.

With use of an electronic picture-scanning device and a digital computer, electron micrographs taken of a specimen along several different directions can be superimposed to form a montage that is more informative than the component images. Preliminary results indicate that one may thus study unstained, unshadowed biological material at high resolution.

Colloids↗