PARAQUAT HERBICIDE DIMINISHES CHEMOREFLEX SENSITIVITY, INDUCES CARDIAC AUTONOMIC IMBALANCE AND IMPAIR CARDIAC FUNCTION IN RATS.
Am J Physiol Heart Circ Physiol. 2021 Jan 29. Epub 2021 Jan 29. PMID: 33513085
Katherin V Pereyra
Paraquat (PQT) herbicide is widely used in agricultural practices despite is highly toxic to humans. It has been proposed that PQT exposure may promote cardiorespiratory impairment. However, the physiological mechanisms involved in cardiorespiratory dysfunction following PQT exposure are poorly known. We aimed to determine the effects of PQT on ventilatory chemoreflex control, cardiac autonomic control and cardiac function in rats. Male Sprague-Dawley rats received 2 injections/week of PQT (5mg·Kgi.p.) for 4 weeks. Cardiac function was assessed through echocardiography and pressure-volume loops. Ventilatory function was evaluated using whole-body plethysmography. Autonomic control was indirectly evaluated by heart rate variability (HRV). Cardiac electrophysiology (EKG) and exercise capacity were also measured. Four-weeks of PQT administration markedly enlarged the heart as evidenced by increases in ventricular volumes and induced cardiac diastolic dysfunction. Indeed, end-diastolic pressure was significantly higher in PQT rats compared to control (2.42± 0.90 vs. 4.01 ± 0.92 mmHg, PQT vs. Control, p<0.05). In addition, PQT significantly reduced both the hypercapnic and hypoxic ventilatory chemoreflex response and induced irregular breathing. Also, PQT induced autonomic imbalance and reductions in the amplitude of EKG waves. Finally, PQT administration impaired exercise capacity in rats as evidenced by a ~2-fold decrease in times-to-fatigue compared to Control rats. Our results showed that 4 weeks of PQT treatment induces cardiorespiratory dysfunction in rats and suggests that repetitive exposure to PQT may induce harmful mid/long term cardiovascular, respiratory and cardiac consequences.