Oliveira PWC, de Sousa GJ, Birocale AM, et al. - Researchers intended to unveil the cardiac autonomic influences of chronic metformin in hypertensive rats. They took 12-week-old male SHR and Wistar rats and grouped them as follows: WN (Wistar normotensive); SC (SHR hypertensive control); and SM (SHR: Metformin 300mg/kg/day for 30 days). In catheterised rats, they analyzed spontaneous and induced (by phenylephrine and sodium nitroprusside) baroreflexes. They also assessed cardiac autonomic tone via heart rate shift by atropine (parasympathetic) or atenolol (sympathetic). They found the resting heart rate and the cardiac sympathetic tone were reduced and baroreflex was improved (particularly in the offsetting of rising BP) in non-diabetic hypertensive rats treated with metformin, although blood pressure and glycaemia continued to be unaltered. Findings revealed anti-inflammatory and antioxidant effects of chronic metformin, and it brought about improvements, independently of changes in glycaemia, in cardiac autonomic parameters that are impaired in hypertension, being associated with end-organ damage and mortality.