Effects of low-level of lead exposure on blood pressure and function of the rat isolated heart
Trauma Monthly: 12 (4); 297-289 Article Type: Research Article
January 1, 2007
January 1, 2007
A. Effects of low-level of lead exposure on blood pressure and function of the rat isolated heart,
Online ahead of Print
Background: Exposure to low levels of lead acetate can induce hypertension in both human and experimental animals. The exact mechanisms of lead-induced hypertension are not well-known, but its pathogenesis could be explained by changes in the heart rate and contractility. Aims. In present study, the effects of 100 ppm lead exposure in drinking water (in the periods of 4, 8 and 12 weeks) on blood pressure and some physiologic parameters (electrocardiography, heart rate, contractility and coronary flow) of isolated rat heart was investigated, using Langendorff isolated heart set up. The isolated hearts were perfused with Krebs-Henseleit solution at 37?C and pH=7.4, gassed with 95% O2 + 5% CO2. All data were digitized by a software program for further analysis. Results: The blood pressure in 8- and 12-week lead-treated groups was significantly increased compared with those of the control group. The ECG findings showed the incidence of arrhythmia and conduction abnormality only in the late phases of exposure (12 weeks). The heart rate (HR) and contractility were significantly higher in 8- and 12-week lead-treated rats but not in 4-week group. Finally, no significant changes were observed in coronary flow. Conclusion: These results indicate that: 1) Low levels of lead exposure in the early phase would not significantly affect ECG. 2) Low levels of lead exposure would impose changes to ECG in the late phases of exposure. 3) This levels of lead exposure can increase HR and cardiac contractility with no effect on coronary flow. Thereby, it can be concluded that observed changes in lead-treated rats might participate in induction of hypertension.
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