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Biomedical subjects

J D Sinclair

Publications and source records attributed to J D Sinclair.

At least 73 records · Page 4Linked to original sources
PubMed1981

Effects of small changes of blood volume on oxygen delivery and tissue oxygenation.

Circulatory effects of small (approximately 10%) changes in blood volume were examined in resting and exercising dogs: controls; group A (-200 ml blood); group B (+200 ml blood); group C (+200 ml 6% dextran). In exercise, cardiac output (Q) increased more in Group A than controls (510.4 ml . kg-1 . min-1 compared to 429.6 ml . kg-1 . min-1; P less than 0.05); oxygen delivery (cardiac output x arterial O2 content) and mixed venous oxygen tension (PVO2) were unchanged from exercising controls. Hypervolemia (group B) did not change Q or O2 delivery compared to controls, but caused a greater reduction in exercise PVO2 (29.3 mmHg compared to 33.1 mmHg in controls; P less than 0.01). Resting PVO2 as raised in group C (50.0 mmHg compared to 46.3 mmHg; P less than 0.05) and exercise PVO2 was reduced less (35.5 mmHg compared to 33.1 mmHg in controls; P less than 0.05). O2 delivery in exercise was higher than in controls (123.4 ml . kg-1 . min-1 compared to 94.3 ml . kg-1 . min-1; P less than 0.001). During exercise, O2 consumption was raised from base line to 34.9 ml . kg-1 . min-1 in controls and raised further to 41.4 ml . kg-1 . min-1 in group A, 44.4 ml . kg-1 . min-1 in group B, and 41.2 ml . kg-1 . min-1 in group C (P less than 0.01). Changes of blood volume that lie within physiological limits thus significantly modify the circulatory response to changed O2 requirements, and also change the metabolic cost of exercise.

Animals↗
PubMed1980

Aldehyde dehydrogenase inhibitors and voluntary ethanol drinking by rats.

Aldehyde dehydrogenase (ALDH) inhibitors, cyanamide (200 mg or 40 mg/kg food) and coprine (N5-(hydroxycyclopropyl)-L-glutamine, 500 mg/kg food), strongly suppressed, with similar time courses, the free-choice consumption of 10% v/v ethanol. The suppression occurred with both continual and alternate access to alcohol. The presence of the inhibitors (plus 4-methylpyrazole to prevent acetaldehyde accumulation) did not affect ethanol-induced (1.5 g/kg i.p.) motor impairment on the tilting plane, but the rats on alternate-day access, which consumed more alcohol on days of access, were significantly less impaired.

Acetaldehyde↗
PubMed1980

The respiratory role of the ventral surface of the medulla studied in the anaesthetized rat.

1. The respiratory role of the ventral surface of the medulla was studied in rats anaesthetized with a urethane-chloralose mixture. 2. In fifty-eight studies on twelve animals, direct superfusion of the medullary surface with artificial c.s.f. made acid by the reduction of bicarbonate content or by the increase of PCO2 produced no significant stimulation of respiration provided that the temperature of the brain surface was unaltered. 3. Superperfusion of the medullary surface with c.s.f. of low bicarbonate content produced an inhibition of respiration in fourteen of thirty-eight experiments. 4. Electrical stimulation on the surface revealed a localized area lateral to the pyramids and rostral to the XIIth nerve where stimulation at low intensity produced an increase in the frequency and depth of respiration. 5. The application of carbachol to a similar region increased both the frequency and amplitude of ventilation at lower concentrations than were required to obtain effects from surrounding areas. 6. Sudden switching between perfusates at different temperatures produced changes of ventilation within 1-2 sec of a change of surface temperature. The Q10 for the ventilation/temperature relationship was approximately 6. 7. The experiments confirm that the ventral surface of the medulla contains neural elements which, at least during urethane-chloralose anaesthesia, have a significant effect on respiration. The stimulus for these effects in the rat does not appear to be a change in H+ concentration. It appears more probable that the primary role of the area lies in the link between thermal and respiratory regulation.

Animals↗
PubMed1979

Alcohol-deprivation effect in rats genetically selected for their ethanol preference.

Alcohol deprivation and alternate-day access increase voluntary alcohol drinking by normal rat strains in a consistent manner. In contrast, the ANA strain developed by selective outbreeding for low alcohol intake during continuous access showed no increase in their alcohol drinking during alternate-day access and only a small increase after a week of deprivation. The AA strain developed for high alcohol intake showed an increase after a week of deprivation similar in magnitude to that of normal rats but persisting much longer. In order to have been selected, these deviant reactions to deprivation must have been related to deviant baseline levels of alcohol drinking during continuous access, but presently even the AAs with the lowest baselines show the persistent increase and the ANAs with the highest baselines show only small increases. Strain differences were also found in spontaneous alternation in a T-maze. A modification of Pinel and Huang's inhibitory factor model accounting for these results is presented.

Alcohol Drinking↗
PubMed1978

Passing remarks.

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Cardiac Catheterization↗
PubMed1976

Thoracic and arterial pressures, blood flow and syncope.

The relationship between elevation of the thoracic pressure and the thoracic volume and blood pressure was investigated in man. Raising the thoracic pressure produced an increasing hypotension and ultimately fainting. Cine-radiography showed a reduction in heart size while the high thoracic pressure was maintained.

Animals↗
PubMed1976

Motivation for alcohol in rats: position and bottle preferences do not cause drinking.

Position preference, i.e., the tendency to drink from onelocation rather than the other, was found to be relatively unimportant in determining the drinking behavior of rats presented with a choice between water and a 7% (v/v) ethanol solution in typical two-bottle choice situations. It accounted for essentially none of the variance in rats generally drinking more alcohol solution than water after prolonged previous alcohol experience, and in rats consuming very little alcohol; only in rats drinking slightly less alcohol solution than water was it found to have an influence. Similarly, bottle preference, i.e., the tendency to drink from one of the two bottles regardless of its position or contents, andposition preference were found to have almost no effect on heavy-drinking rats even on their first day of exposure and on low-drinking rats after about three days of access to alcohol.

Alcohol Drinking↗