Effect of hydrogen peroxide on rabbit urinary bladder citrate synthase activity in the presence and absence of a grape suspension

Abstract

Purpose: The etiology of obstructive bladder dysfunction includes free radical damage to mitochondria. Feeding rabbits a standardized grape suspension protects the ability of the bladder to contract and empty in part by preventing mitochondrial damage, thus maintaining smooth muscle and mucosal metabolism. The objective of the current study is to determine the direct effect of this grape suspension on the response of mitochondria to the oxidative effects of hydrogen peroxide. Materials and Methods: Six male rabbits were anesthetized with sodium pentobarbital and the bladders excised. Four full thickness strips were obtained for contractile studies and the balance separated into smooth muscle and mucosa compartments by blunt dissection. The effect of hydrogen peroxide on the contractile response to field stimulation was quantitated. Each tissue was homogenized and the effects of increasing concentrations of hydrogen peroxide in the presence and absence of grape suspension on citrate synthase activity was determined. Results: Citrate synthase activity was significantly higher in the mucosa than in the muscle. The grape suspension had no effect on control citrate synthase activity. However, the grape suspension provided significant protection of both smooth muscle and mucosal citrate synthase activity. Conclusions: These studies support the conclusion that the grape suspension provides direct protection of mitochondrial function.

A Comparison of Total Antioxidant Capacities of Concord, Purple, Red, and Green Grapes Using the CUPRAC Assay

“…The TAC of grapes in general has been effectively demonstrated in studies where a grape powder suspension has been fed orally to rabbits subjected to a variety of forms of in vivo and in vitro ischemia/reperfusion and partial outlet obstruction with all models producing significant oxidative damage to the urinary bladder. These studies clearly demonstrated that oral grape ingestion reduced both oxidative damage to proteins and lipids and significantly protected the rabbit urinary bladder from both structural and contractile damage [ 33 , 34 , 35 , 36 ]. It should be noted that this grape suspension was standardized by the California Table Grape Commission and consisted of a freeze-dried powder of a variety of table grapes grown in California.…”