Treatment with prazosin (0.15 mg/kg) preserved left ventricle internal dimensions in diastole and cardiac output (n = 8 per group). (A and B) Echocardiographic assessments of the rat by M-mode in the 6-hydroxydopamine (6-OHDA) group and with prazosin treatment (n = 8 per group). (C) The decrease in left ventricle internal dimensions in diastole was reversed at 3 and 6 h in the 6-OHDA plus prazosin group compared with that in the 6-OHDA group. (D) The left ventricle internal dimensions in systole were decreased at 3 and 6 h in the 6-OHDA group but were reversed at 6 h and increased to baseline at 12 h after prazosin treatment. (E) The decreased cardiac output at 3 and 6 h in the 6-OHDA group was preserved with prazosin treatment with higher cardiac output at 6 and 12 h (perhaps due to the increased heart rate). (F and G) The acute increase of the interventricular septum thickness in diastole and left ventricle posterior wall thickness in diastole were reversed at 3 and 6 h in the 6-OHDA plus prazosin group compared with that in the 6-OHDA group. The data represent the means ± SD. *P < 0.05 and **P < 0.001 versus the respective group at 0 h; †P < 0.05 and ††P < 0.001 versus the respective group at 3 h; ‡P < 0.05 versus the respective group at 6 h; §P < 0.05 and §§P < 0.001 6-OHDA versus 6-OHDA plus prazosin.