Toxicity and carcinogenicity studies of phenylephrine hydrochloride in F344/N rats and B6C3F1 mice

Enhancement of the murine primary antibody response by phenylephrine in vitro

Phenylephrine was found to enhance the primary (immunoglobulin M) antibody response of murine splenocytes to sheep erythrocytes when added to splenocyte cultures at the time of in vitro immunization. The enhancement was seen at all times during the developing antibody response. One day after the peak response the enhancement was 78% above the control response, and was completely blocked by equimolar concentrations of the alpha adrenoceptor antagonist phentolamine. The alpha-1 adrenoceptor antagonist prazosin dose dependently antagonized the enhancement associated with phenylephrine one day after the peak response. These results suggest that phenylephrine prolongs the in vitro IgM antibody response by way of alpha-1 adrenoceptor activation. The adrenoceptors responsible for this pharmacologic response could not be demonstrated using direct radioligand binding techniques.