Twenty-Four-Hour Variations in the Sensitivity of Rat Aorta to Vasoactive Agents
- 1 January 1996
- journal article
- research article
- Published by Informa UK Limited in Chronobiology International
- Vol. 13 (6), 465-475
- https://doi.org/10.3109/07420529609020917
Abstract
The presence of time-dependent variations in the in vitro sensitivity of aorta preparations to either vasoconstricting or relaxing agents was investigated in rats maintained in light for 08:00 to 20:00 and in darkness from 20:00 to 08:00. Rat thoracic aorta rings were obtained from animals sacrificed at four different times of the day. The rat aorta was found to be sensitive to the constricting effect of phenylephrine at 15:00, and of 5-hydroxytryptamine at 21:00. On the other hand, both endothelium-dependent and -independent relaxations were more remarkable at 03:00 than at other times of the day. These variations represented significant circadian rhythms when analyzed by analysis of variance. Different in vitro responsiveness to these agents might reflect changes in the sensitivity and/or number of related receptors in vascular preparations. In conclusion, the circadian time of animal sacrifice to obtain vascular preparations constitutes an important aspect of the research method and a key determinant of findings.Keywords
This publication has 18 references indexed in Scilit:
- Circadian blood pressure changes and left ventricular hypertrophy in essential hypertension.Cell Metabolism, 1990
- Major circadian fluctuations in fibrinolytic factors and possible relevance to time of onset of myocardial infarction, sudden cardiac death and strokeThe American Journal of Cardiology, 1988
- Morning increase in platelet aggregability. Association with assumption of the upright posture.Cell Metabolism, 1988
- Concurrent Morning Increase in Platelet Aggregability and the Risk of Myocardial Infarction and Sudden Cardiac DeathNew England Journal of Medicine, 1987
- Circadian variation of transient myocardial ischemia in patients with coronary artery disease.Circulation, 1987
- Circadian Rhythms of Epinephrine and Norepinephrine in Man*Journal of Clinical Endocrinology & Metabolism, 1985
- CIRCADIAN VARIATION OF BLOOD-PRESSUREThe Lancet, 1978
- Twenty-four Hour Pattern of the Episodic Secretion of Cortisol in Normal SubjectsJournal of Clinical Endocrinology & Metabolism, 1971
- Blood Fibrinolytic Activity in ManCirculation Research, 1970
- A diurnal rhythm in plasma renin activity in man.JCI Insight, 1966