Fig. 8.
Effects of organ culture and NO donor DETA-NO on cGMP-activated phosphotransferase activity measurements in the soluble fraction of homogenates prepared from porcine PA. The maximal cGMP-activated phosphotransferase activity (apparent Vmax) was decreased relative to that obtained from freshly prepared PA (▵) in 24-h cultured PA (○) and was further decreased in PA cultured for 24 h with DETA-NO (•). The cGMP concentration ([cGMP]) at which 50% of Vmax (apparent cGMP KA) was attained did not differ significantly between the different treatment groups. Specific activity (phosphotransferase activity/ng cGKI present in homogenate) was measured with [cGMP] 0 and 100 μM (right). 0 h, 24 h, and 24 h NO, freshly prepared and 24 h cultured without and with DETA-NO. Maximal cGMP-activated phosphotransferase specific activity measured was the same in freshly prepared and 24-h cultured PA but was significantly reduced in PA cultured for 24 h with DETA-NO. Data are means ± SE; n = 6. *Different (P < 0.05) from freshly prepared and 24-h cultured PA.