Bovine platelets retain functional activity in the presence of penicillin G

It has been reported that antibiotics of the penicillin family impair the functional response of human, canine and lapine platelets to a broad range of agonists. In contrast, we have shown that the bovine platelet retained full functional responses to stimulation by adenosine diphosphate (ADP) or platelet activating factor (PAF) following administration of penicillin G to clinically normal cattle at 20,000 IU/kg for three days. The aggregation response to collagen was transiently reduced to approximately 50% of pretreatment values, but only while the drug was detectable in the circulation. When penicillin was added to platelet rich plasma suspensions, ADP-induced aggregation was similar to that of the control untreated platelets, while the PAF-induced aggregation response was reduced by not more than 25%. Only collagen-induced aggregation exhibited a modest dose-dependent inhibitory response in the presence of penicillin. It is postulated that the relative insensitivity of the bovine platelet to penicillin may be related to differences in postreceptor biochemical events compared to the human platelet.