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  • Title: [Assessment of the Bezold-Jarisch reflex in experimental myocardial infarction].
    Author: Meyrelles SS, Mill JG, Vasquez EC.
    Journal: Arq Bras Cardiol; 1995 Jun; 64(6):521-4. PubMed ID: 8561670.
    Abstract:
    PURPOSE: To evaluate the cardiogenic depressor Bezold-Jarisch reflex in rats with chronic myocardial infarction. METHODS: Adult Wistar rats were submitted to ligation of the anterior descending coronary artery of the left ventricle (group INF, n = 15) and compared with rats submitted to sham-operation (group Sham, n = 15). Thirty days after the surgery, without influence of anesthetics, the basal mean arterial pressure (MAP) and heart rate (HR) were measured. Immediately after, the Bezold-Jarisch reflex was evaluated measuring the falls in diastolic arterial pressure (DAP) and the simultaneous bradycardia induced by injections of 5-hydroxytryptamine (5-HT, 4 to 32 micrograms/kg, i.v.). RESULTS: The INF group showed significantly lower basal MAP and HR values (103 +/- 3 mmHg and 328 +/- 6 bpm) when compared to the Sham group (110 +/- 2 mmHg and 348 +/- 7 bpm). The Bezold-Jarisch reflex was significantly attenuated in the INF group (falls of DAP from 2 +/- 2 to 31 +/- 3 mmHg and HR from 8 +/- 5 to 204 +/- 15 bpm), when compared to the Sham group (falls of DAP from 10 +/- 3 to 41 +/- 3 mmHg and HR from 58 +/- 12 to 276 +/- 16 bpm). The morphological analysis showed a myocardial infarction mainly located at the anterolateral portion of the left ventricle with a maximal extension of 35% of the left ventricle circumference. The INF group showed right ventricular and left atrial hypertrophy when compared to the Sham group. CONCLUSION: The experimental chronic myocardial infarction in rats is followed by significant attenuation of the Bezold-Jarisch reflex, probably as result of a heart failure and, consequently, of functional alterations in the chemosensitive receptors of cardiac unmyelinated vagal afferents.
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