Disturbance of cardiovascular circadian rhythms by pertussis vaccine in freely-moving rats

Vaccination of young children with diphtheria, tetanus, poliomyelitis and p ertussis (DTPoP) vaccine is effective in preventing outbreaks of whooping c ough but adverse events sometimes occur. This pilot study shows that in fre ely-moving rats, multiple treatment with DTPoP (at day 0 and day 5, 6 ml/kg i.v.) increased heart rate (HR) for 5 days after the first treatment and d ecreased diastolic blood pressure (DBP) for at least 26 days after the firs t treatment and inhibited the circadian rhythm of HR and DBP for at least 1 0 days. DTPo vaccine, containing no pertussis vaccine, was free of such eff ects. Thus, in rats, the pertussis component of DTPoP acts on the cardiovas cular system and disturbs its circadian rhythm. The contribution of these f indings to clinical adverse effects is as yet unknown and needs further res earch.