The effect of Shenmai injection on cardiac systolic and diastolic function of isolated myocardial infarction model rats

Objective To observe the effect of Shenmai injection on isolated cardiac systolic and diastolic function in myocardial infarction rats. Methods 32 rats were randomly divided into a control group, a propranolol group, a Shenmai + propranolol group and a Shenmai group. The myocardial infarction models were made by ligating the left anterior descending coronary artery of rats .The heart was taken from myocardial infarction rat after 3 days. The indexes of Isometric tension (IT), Diastolic tension (DT), heart rate (HR), the maximum pressure ascending and descending rate of left ventricle (± LVdp/dtmax) (mmHg/s) were recorded by using Langendorff isolated heart perfusion technique at 5min before and 0.5 h, 1 h, 2 h after perfusion. Results Compared with the control group, the IT (2.01 ± 0.02 g, 1.52 ± 0.01 g, 1.53 ± 0.02 g), the HR (326 ± 32 time/min, 331 ± 41 time/min, 307 ± 37 time/min) and the ±LVdp/dtmax (4 012 ± 193 mmHg/s, 3 729 ± 174 mmHg/s, 3 631 ± 123 mmHg/s; 3 565 ± 202 mmHg/s, 3 632 ± 154 mmHg/s, 3 601 ± 129 mmHg/s) were apparently decreased in the propranolol group at 0.5 h, 1 h, 2 h after perfusion, and the differences were statistically significant (P 0.05). Conclusions Shenmai injection can improve myocardial contractility in isolated heart of myocardial infarction rats, however, propranolol can completely block the strong heart effect of Shenmaiinjection. This suggests that Shenmai injection has a beta receptor agonist effect. Key words: Myocardial infarction; Heart rate; Isometric tension; Diastolic tension; Shenmai injection; Propranolol