The cardiac adenyl cyclase - cyclic amp system in ethanol treated Sprague Dawley and spontaneously hypertensive rats

Abstract

The left ventricular adenyl cyclase - cyclic AMP system was examined in 20-week-old/male Sprague Dawley (SD) and spontaneously hypertensive (SHR) rats treated with ethanol. Treatment consisted of intraperitoneal injections of ethanol (3.0g/kg) every twelve hours for five days. Control animals received equivalent volumes of physiological, saline. Following the last treatment the rats were anesthetized with ketamine hydrochloride and a teflon catheter was placed in the right carotid artery to measure heart rate and mean arterial pressure. Subsequently the hearts were removed and cut into 4 mm cross sectional blocks of tissue, frozen din a hexane bath cooled to -78 °C with dry ice, and stored at -70 °C. Frozen 10 m thick sections were used for enzymatic histochemical analysis of adenyl cyclase and cyclic nucleotide phosphodiesterase. Immunohistochemical procedures were employed to determine the activity of cyclic AMP and calmodulin. Heart rates (HR) (mean beats/minute [plus or minus] SE] were as follows: SD, ethanol-treated: 381 [plus or minus] 15.9; Sd, saline-treated: 357 [plus or minus] 15.9; SHR, ethanol-treated 319 [plus or minus] 14.9; and SHR, saline-treated: 362 [plus or minus] 17.2 (p>0.05). Mean arterial pressure (MAP) (mm Hg [plus or minus] SE) were as follows: SD, ethanol-treated: 85 [plus or minus] 6.9; DS, saline-treated: 136 [plus or minus] 6.9; SHR, ethanol-treated: 125 [plus or minus] 7.5; and SHR saline-treated: 187 [plus or minus] 7.5 (p<0.05). Adenyl cyclase (AC) activity mean [plus or minus] SE) was as follows: SD, ethanol treated: 0.17 [plus or minus] 0.02; SD, saline-treated: 0.12 [plus or minus] 0.02; SHR, ethanol-treated: 0.19 [plus or minus] 0.02; and SHR, saline treated: 0.12 [plus or minus] 0.02. AC activity was significantly higher in ethanol treated animals, and this elevation appeared to be independent of strain (p<0.05)...