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Biomedical subjects

B Cox

Publications and source records attributed to B Cox.

252 records · Page 14Linked to original sources
PubMed1971

Investigation of the mechanism of action of oxotremorine on the guinea-pig isolated ileum preparation.

1. The effects of oxotremorine on the guinea-pig ileum have been investigated to determine whether any component of its action is due to acetylcholine release.2. Log dose-response curves to oxotremorine and acetylcholine were similar and both drugs were competitively antagonized by atropine.3. Mipafox potentiated acetylcholine but not oxotremorine.4. No evidence of an indirect component of the action of oxotremorine was obtained using various pharmacological procedures (tetrodotoxin, morphine, cooling, procaine and hemicholinium-3).5. Oxotremorine had no effect on acetylcholine release from mipafox treated ileum but decreased the release from physostigmine treated ileum.6. It is concluded that oxotremorine acts directly on muscarinic receptors and not by releasing acetylcholine.

Acetylcholine↗
PubMed1970

Effects of drugs on tremor and increase in brain acetylcholine produced by oxotremorine in the rat.

1. In rats the effect of drugs on oxotremorine tremor and oxotremorine-induced increase in brain acetylcholine has been investigated.2. Reserpine, (+/-)-alpha-methylmetatyrosine and diethyldithio-carbamic acid, drugs which have in common the ability to decrease tissue noradrenaline concentration, inhibited oxotremorine tremor without preventing the oxotremorine-induced increase in brain acetylcholine.3. (+/-)-p-chlorophenylalanine, a depletor of tissue 5-hydroxytryptamine, did not inhibit oxotremorine tremor.4. Phenoxybenzamine and propranolol inhibited oxotremorine tremor, and propranolol was without effect on oxotremorine-induced increase in brain acetylcholine.5. The toxicity of oxotremorine was increased by reserpine and phenoxybenzamine.6. The significance of these findings is discussed with regard to the mode of action of oxotremorine.

Acetylcholine↗
PubMed1969

The effects of atropine and dyflos on tremor and increase in whole brain acetylcholine produced by injection of oxotremorine in the rat.

1. Injection of oxotremorine in the rat results in tremor and an increase in brain acetylcholine. The effects of atropine and dyflos have been investigated on both these actions.2. Atropine decreased brain acetylcholine concentration and inhibited oxotremorine-tremor. It did this in doses which did not prevent the oxotremorine-induced increase in whole brain acetylcholine.3. Dyflos increased brain acetylcholine concentration, but it was without effect on oxotremorine tremor. Some mutual antagonism was observed between the actions of oxotremorine and dyflos on rat brain acetylcholine concentration.4. These results do not support a causal relationship between the increase in whole brain acetylcholine and the tremor produced by oxotremorine.

Acetylcholine↗
PubMed1969

The relationship between tremor and change in brain acetylcholine concentration produced by injection of tremorine or oxotremorine in the rat.

1. The relationship between tremor and change in brain acetylcholine concentration after the injection of tremorine or oxotremorine has been investigated in rats.2. Tremorine produced a significant increase in whole brain acetylcholine and in tremor 5 min after injection. After this time tremor subsided but brain acetylcholine continued to increase.3. Oxotremorine produced tremor within 30 sec. This became maximal within 5 min of injection and then declined rapidly. The brain acetylcholine concentration showed a significant increase 5 min after injection and continued to increase until 30 min afterwards.

Acetylcholine↗
PubMedDate not supplied

Behavioral thermoregulation in the study of drugs affecting body temperature.

A method of measuring thermoregulatory behavior in the rat has been developed, which allows analysis of the mechanism of action of drugs which modify body temperature. The test measures the amount of time a rat will remain exposed to an infrared heat source before making an escape and this evidence has been used to divide drugs into those which act on the central thermostats and those which act on effector systems. A peripherally acting hypothermic drug (N-methyldiphenhydramine) increased the time of exposure to the heat lamp. Tri-iodothyronine increased body temperature and decreased exposure to the heat lamp. Intraventricular oxotremorine caused hypothermia but a decreased exposure to heat suggesting it acts to lower the set-point of the central thermostats. Both effects were blocked by atropine. The possibility that central cholinergic mechanisms in the hypothalamus have a function in determining the setting of the central thermostats is discussed.

Animals↗
PubMedDate not supplied

Symptoms of low blood pressure: a population study.

OBJECTIVE: To establish whether an association exists between blood pressures in the "low normal" range and common symptoms such as tiredness, dizziness, headache, and palpitation, as suggested by French and German medical practice but not English or American medical practice. DESIGN: Cross sectional population based survey (the health and lifestyle survey) of blood pressure measurements and self reported common symptoms. Results were analysed by combined stratification and logistic regression. SUBJECTS: 7383 (82%) Adults aged 18 and over chosen from the electoral register in England, Wales, and Scotland for the health and lifestyle survey, in whom satisfactory physiological measurements were taken, from 9003 in the interviewed sample. MAIN OUTCOME MEASURES: Body mass index, smoking, social class, exercise, self declared physical illnesses, hours slept, use of drugs, and psychological illness as determined with the general health questionnaire assessed as potential confounders. RESULTS: True confounders were sex, age, taking of drugs, physical illness, exercise, and body mass index. A negative association was found between systolic blood pressure and self reported tiredness and feeling faint, which persisted after adjustment for the confounders. The association was strongest in women aged under 50. A negative association between systolic blood pressure and headache and a positive association between systolic blood pressure and palpitation were explained by confounding by age. CONCLUSIONS: Systemic hypotension is associated with persistent tiredness but treatment is not suggested as either possible or necessary. Instead, low blood pressures may be associated with opposite effects on mortality contrasted with morbidity.

Adolescent↗