Biological-time-dependent differences in effect of verapamil on rat aorta and influence of endothelium

Guney H., Uluoglu C., Hodoglugil U., Gorgun C., Yamanoglu T., Abacioglu N., ...More

CHRONOBIOLOGY INTERNATIONAL, vol.16, no.6, pp.779-787, 1999 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 16 Issue: 6
  • Publication Date: 1999
  • Doi Number: 10.3109/07420529909016945
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.779-787
  • Gazi University Affiliated: No


The biological-time-dependent variation in the vasodilator effect of verapamil on rat thoracic aorta was assessed in both endothelium-intact and denuded preparations. Groups of adult male rats were housed in light from; 08:00:to 20:00 and in darkness from 20:00 to 08:00 and sacrificed at six different times of the day (1, 5, 9, 13, 17, and 21 hours after lights on; HALO). Verapamil caused concentration-dependent relaxations in both endothelium-intact and denuded aortic rings precontracted with phenylephrine (Phe). In endothelium-intact rings, neither the AUC nor: the EC50 values for verapamil exhibited significant biological-time-dependent effects as determined by one-way analysis of variance (ANOVA). In endothelium-denuded rings, AUC values did vary in a statistically significant manner according to the biological time of study, while the EC50 values did not. Endothelium denudation led to an increase in EC50 values at almost every time: point, Statistically significant interactions between the biological time of study and treatment (intact vs. denuded endothelium) in both AUC and EC50 values were:documented by two-way ANOVA; this indicated. differences in the clock-time staging of verapamil-induced relaxation in endothelium-denuded versus intact aortic rings.