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PubMedDate not supplied

[Interaction of inotropic effects on acetylcholine, adrenaline and increase of atrium stimulation frequency in rats adapted and non-adapted to physical exercise].

It is shown in experiments carried out on the isolated strips of the left and right atria of the rat that adrenaline decreases the inotropic effect of acetylcholine while interatrial differences of chrono-inotropy are elevated by acetylcholine and adrenaline. Training of animals changes interaction of regulatory effects in such a way that an increase of the negative chrono-inotropy is compensated and efficiency of the cardiac muscle regulation grows.

Acetylcholine↗
PubMed1989

Dark adaptation and recovery from light adaptation: smokers versus nonsmokers.

Because the published data concerning the effects of smoking on visual sensitivity at night are inconsistent, a new study was initiated to obtain ground level comparison data from smoking and nonsmoking Army aviators. Blood samples also were analyzed to compare serum levels of nicotine, cotinine, and carboxyhemoglobin with the visual measures. The present data show no differences in visual sensitivity between smokers and nonsmokers and no significant correlations between the blood and visual measures. The conclusion from these results is that the ability to see the dimmest lights at night is independent of smoking history when scotopic sensitivity is assessed at ground level.

Adult↗
PubMed1988

Temporal integration of stimulus increments under chromatic adaptation: effects of adaptation level, wavelength, and target size.

The threshold-duration functions were determined for a 520-, 570-, or 650-nm test presented upon the various monochromatic backgrounds. The variation of the threshold-duration functions with the background intensity, taken with the 520- or 650-nm test, showed a strong dependence on the background wavelength. This wavelength difference became prominent for the high background intensities: for the bright 570-nm background, partial summation occurred for the duration range from 50 to 200 msec, while such a partial summation effect was very small for the bright 520- and 650-nm background. Test for test-mixture additivity indicated that the longer integration time, obtained for the 520- or 650-nm test with the 570-nm background, was attributed to contribution of the opponent-color process. The elongation of the temporal integration period was found to be affected by the size of the test target. The interrelation among temporal and spatial summation, background intensity, and wavelength could be accounted for by temporal integration of the opponent-color process in addition to that of the cone mechanisms.

Adaptation, Ocular↗