A pharmacological analysis of the responses of isolated aorta from rats with adjuvant arthritis.

In order to investigate whether chronic inflammation alters the reactivity of vascular smooth muscle, the effects of various agonists have been compared on isolated aortae from rats with and without arthritis. No significant differences in the EC50 values and maximal responses to 5-hydroxytryptamine (5-HT), noradrenaline (NA) and potassium chloride (KCl) were observed. When calcium was removed from Krebs solution the responses to 5-HT and NA were significantly higher in the preparations from arthritic rats. Verapamil had the same inhibitory effect on the responses of both groups. This suggests that the reactivity of the aortic smooth muscle from arthritic rats is less dependent on extracellular calcium than that of the control preparations.