Acute cardio-respiratory effects in rats of PS4alpha, an antineoplastic peptidoglycan from Mycobacterium vaccae

PS4alpha is a high molecular weight peptidoglycan extracted from Mycobacterium vaccae, which has demonstrated considerable antineoplastic activity in-vivo without apparent toxicity. Available fortesting in only small quantities, a sensitive in-vivo method for measuring pulse and breathing rates in cannulated rats was applied to this compound at doses of 5, 50 and 500 microg kg(-1). Various parameters (mean arterial pressure, maximum transpulmonary pressure, compliance, heart rate, minute volume, respiratory rate and tidal volume) were followed for up to 1 h and demonstrated no significant deviation in the baseline values obtained before injection. This compound at doses up to 500 microg kg(-1) had no apparent acute toxicity in rats, but chronic effects at this and higher doses have to be determined by more conventional toxicological methods before proceeding to evaluate PS4alpha as an antineoplastic agent.