Calcium movements in aortae from arthritic rats.

40Ca content, 45Ca uptake, influx and efflux were measured in aortae from arthritic rats. 40Ca content measured by atomic absorption spectrometry was higher in aortae from arthritic than from normal controls. 45Ca uptake, inflow and outflow were also enhanced in aortae from arthritic rats whether under basal or stimulated conditions (e.g. in the presence of high potassium or noradrenaline). Verapamil failed to inhibit basal 45Ca uptake but normally inhibited 45Ca inflow stimulated by high potassium or noradrenaline in both aortic preparations. No histological difference was detected by optical microscopy between normal and arthritic aortae. It is concluded that aortae from adjuvant arthritic rats are apparently characterized by a higher intracellular Ca++ content resulting from enhanced Ca++ inflow through at least three Ca++ pathways. This higher intracellular content may explain why aortae from arthritic rats are less dependent on extracellular Ca++ than aortae from normal rats when stimulated by agonists like serotonin and noradrenaline.