Objective: 

The aim of the study was to evaluate the effects of curcumin treatment on the vascular responses to 5-hydroxytryptamine (5-HT) and potassium chloride (KCl), both of which cause receptor-dependent and receptor-independent contractions, respectively and also to examine the role of nitric oxide in these responses.

Methods: 

The study protocol was approved by the Ethics Committee of the Selçuk University Experimental Medicine Research and Application Center. The rats were randomly divided into two groups: Control and curcumin-treated (200 mg/kg/day, p.o., for 4 weeks). After four weeks rats were sacrificed by cervical dislocation. The descending thoracic aorta was quickly isolated, cleaned, and sectioned into 3- to 4-mm-long rings. The rings were then placed in organ baths. Changes in isometric tension were recorded by a force-displacement transducer. Starting from each aorta, a single ring was sent for pathological research.

Results: 

The concentration response curves to 5-HT (10-9-3x10-4 M) and KCl (5–100 mM) were shifted to the right and the maximal response was significantly decreased in curcumin-treated rat aortas. Pretreatment of rings with L-NAME (a NOS inhibitor, 10–4 M) was increased both in the sensitivity and maximal response to only 5-HT. No apparent histological changes were demonstrated in smooth muscle and connective tissue layers in the aortas of control and curcumin-treated rat preparations.

Conclusions: 

The results of the present study suggest that pretreatment with curcumin decreases the sensitivity and maximal response to both 5-HT and KCl, and in curcumin-treated rat aorta NO release from endothelial cells modulates contraction induced by 5-HT, but not by KCl.