Effects of chronic moderate alcohol consumption and novel environment on heart rate variability in primates (Macaca fascicularis)

Rationale: The effects of chronic moderate alcohol consumption on cardiac function are not understood. Acute stress may affect cardiac function by shifting autonomic cardiac regulation in favor of the sympathetic nervous system. Although alcohol consumption often increases at times of stress, the interactive effects of stress and chronic moderate alcohol consumption on cardiac regulation have not been studied. Objectives and methods: The objective was to assess the effects of long-term (1-2 years) moderate (a two-drink/day equivalent, 5 days/week) alcohol consumption on heart rate (HR) variability under normal and acutely stressful conditions in small stable groups of ovariectomized adult cynomolgus monkeys (Macaca fascicularis). Monkeys were trained to voluntarily drink their daily alcohol dose (<30 min), and blood levels were determined an hour later. The animals were acutely stressed by removal from the home cage to a novel environment for 30 min. HR in freely moving subjects was recorded via telemetry in the home cage and the novel environment. Results: Acute stress increased HR, decreased HR variability, and decreased the high frequency component of the power spectrum suggesting reduced parasympathetic cardiac modulation. Chronic moderate alcohol consumption decreased HR variability and the low frequency components of the power spectrum. When stressed, monkeys with a history of chronic moderate alcohol consumption had higher HRs than the controls. Conclusions: HR dynamics in monkeys rapidly respond to acute stress. Chronic moderate alcohol consumption may be deleterious to cardiac function. HR response to stress may be exaggerated when accompanied by a history of chronic moderate alcohol consumption.