Phosphodiesterase type 2 distribution in the guinea pig urinary bladder

Nitric oxide-stimulated cGMP synthesis represents an important signalling pathway in the urinary bladder. Inhibitors of the PDE1 and PDE5 enzyme have been studied to treat storage and voiding disorders in clinical settings. The distribution of PDE2 in the bladder is unknown. This study focuses on the distribution and site of action of PDE2 within the guinea pig urinary bladder wall. Six male guinea pig bladders were dissected and treated in 2 ml Krebs' solution and 10 A mu M of the specific PDE2 inhibitor, Bay 60-7550 at 36 A degrees C for 30 min. After stimulating tissues with 100 A mu M of diethylamine-NONOate for 10 min, the tissues were snap frozen and cut in 10 A mu m sections which were examined for cGMP immune-reactivity, co-stained with either vimentin, synaptic vesicle protein 2, calcitonin gene-related protein and protein gene product 9.5. PDE2 inhibitor Bay 60-7550 inhibits cGMP breakdown the most in the urothelial and suburothelial layers, as well as on the nerve fibres. After inhibition by Bay 60-7550, cGMP was mainly expressed in the intermuscle interstitial cells and the nerve fibres of the outer muscle layers of lateral wall, indicating the presence of PDE2 activity. Our study is the first to show the distribution of PDE2 in the bladder which was shown to be present in the urothelium, mainly umbrella cells, the interstitial cells of the suburothelium and the outer muscle, as well as in nerve fibres.