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Biomedical subjects

B Cox

Publications and source records attributed to B Cox.

At least 199 records · Page 11Linked to original sources
PubMed1978

Is acetylcholine involved in a dopamine receptor mediated hypothermia in mice and rats?

1 Apomorphine and oxotremorine caused a dose-related fall in core temperature in the mouse and a fall in core temperature preceded by an increase in tail-skin temperature in the rat.2 In both species the slope of the dose-response curve was greater for oxotremorine (8.2 +/- 0.6 mice, 0.9 +/- 0.1 rats) than it was for apomorphine (1.7 +/- 0.3 mice, 0.5 +/- 0.07 rats).3 The mouse was more sensitive than the rat to the effects of both agonists.4 Atropine (0.625 to 5 mg/kg) and hyoscine (0.5 and 1 mg/kg) caused a dose-related rightward shift of the dose-response curve to oxotremorine in mice, but pimozide (0.25 to 1 mg/kg) was ineffective. Similar results were obtained in the rat.5 Pimozide (0.125 to 1 mg/kg) caused a dose-related rightward shift of the dose-response curve to apomorphine in mice, but atropine (1.25 to 1 mg/kg) and hyoscine (0.5 and 1 mg/kg) were ineffective. Similar results were obtained in the rat.6 Intrahypothalamic injection of apomorphine (10 mug) and oxotremorine (1.25 mug) caused a fall in core temperature in rats. Pimozide (0.5 mg/kg i.p.) caused reversal of the effect of apomorphine but did not significantly change the response to oxotremorine. Atropine (2.5 mg/kg i.p.) blocked the effect of oxotremorine, but not that of apomorphine.7 These results suggest that there are both central dopamine and central muscarinic acetylcholine receptors which mediate a fall in core temperature in rodents, but do not support the hypothesis that any connection exists between these two receptor populations.

Acetylcholine↗
PubMed1977

Analysis of the cycling and noncycling cell population of human solid tumors.

The size and kinetics of the cell population of six advanced human solid tumors were analyzed following the continuous infusion of H3-TDR for a period of 6 to 21 days. By using the labelling indices of the cells in interphase and mitosis, and the rate of label incorporation, it was found the only 10 to 40% of the tumor cell population was replicating at any given time. Fifty-five percent to 85% of the remaining cell mass eventually entered into cycle at least once. Anywhere from 5% to 40% of the cell population remained arrested in G2 or G0 in individual cases during the period of observation. The significant size of the "resting" cell compartment is undoubtedly one explanation for the relative insensitivity of advanced adult solid tumors to current cell cycle-oriented therapeutic regimens.

Adenocarcinoma↗
PubMed1977

Do central dopamine receptors have a physiological role in thermoregulation?

1 Core and tail skin temperature was measured in rats which had guide cannulae implanted into their brains to allow drug injections directly into the preoptic anterior hypothalamus. 2 Apomorphine and dopamine (10 microgram in 1 microliter) injected into the area of the preoptic anterior hypothalamus caused a fall in core temperature which was preceded by a rise in tail skin temperature. 3 The decrease in core temperature following central injection of either apomorphine or dopamine was significantly reduced by pretreating rats for 2 h with pikozide 0.5 mg/kg i.p.). 4 Bilateral intrahypothalamic injection of pimozide (0.5 microgram in 1 microliter) significantly reduced the hypothermic effect of systemic apomorphine (1.25 mg/kg i.p.). 5 Control rats placed 65 cm below a 250 W infrared lamp responded with vasodilation of tail skin blood vessels as indicated by an increase in tail skin temperature. Pimozide pretreatment (0.5 mg/kg i.p.) significantly reduced this response. 6 These results suggest that the preoptic anterior hypothalamus contains dopamine receptors which mediate hypothermia in rodents and raise the possibility that endogenous dopamine has a physiological role in thermoregulation.

Animals↗
PubMed1977

Dopaminergic mechanisms in precipitated withdrawal in morphine-dependent rats.

Rats were made dependent on morphine by implantation of a pellet and withdrawal was precipitated by the injection of naloxone 72 hours later. Withdrawal was assessed by scoring each of the following signs individually: chewing, licking, teeth chattering, facial tremor, grooming, writhing, diarrhea, weight loss, wet dog shakes, head shakes and hypothermia. The role of dopamine in withdrawal was determined by pretreating the animals with apomorphine or pimozide. Apomorphine in the lower dose range (0.625-1.25 mg/kg) produced a significant decrease in teeth chattering, writhing, weight loss and wet dog shakes. The high dose of apomorphine (2.5 mg/kg) significantly inhibited all features of the withdrawal except writhing and weight loss. Pimozide caused a significant increase in chewing, writhing and head shakes, but only with the highest dose used (0.5 mg/kg). Pimozide (0.5 mg/kg) significantly reduced withdrawal hypothermia, but apomorphine had no effect on this sign except at the highest dose when withdrawal hypothermia was increased.

Animals↗