Calcium effects on superoxide dismutase and catalase of the rabbit urinary bladder muscle and mucosa.

PURPOSE: Superoxide dismutase (SOD) and catalase are two important antioxidant mechanisms that work together to reduce free radical damage. Intracellular free calcium in smooth muscle can change rapidly and many enzymes can be affected. The sensitivity of SOD and catalase activity to calcium was determined in both rabbit bladder smooth muscle and mucosa.

MATERIALS AND

METHODS

Calcium sensitivity was analyzed by determining SOD and catalase activity in muscle and mucosa at the following calcium concentrations: 0 (in the presence of 1 mM EGTA), 1 and 5 mM CaCl(2).

RESULTS

SOD: EGTA resulted in increased SOD activity of bladder smooth muscle, whereas both 1 and 5 mM calcium significantly decreased SOD activity. EGTA had no effect on SOD activity of the mucosa whereas 1 and 5 mM calcium decreased SOD activity of the muscle. Catalase: 1 mM calcium resulted in decreased catalase activity of the muscle and no change in the activity of the mucosa, whereas 5 mM calcium resulted in increased catalase activity of the mucosa but no change in the activity of the muscle.

DISCUSSION: Mucosa showed more SOD and catalase activity than the muscle. Both SOD and catalase showed differing sensitivities to EGTA and calcium.