The effects of beta-adrenergic agonists on cone systems in the cat eye

The effects of the beta-adrenergic agonist nylidrin and the beta 2-adrenergic agonist clenbuterol on electroretinogram and optic nerve response were studied in the isolated and arterially perfused, light-adapted cat eye. Two cone mechanisms, short wavelength-sensitive and long wavelength-sensitive, were functionally separated by means of intense yellow adaptation. A reversible increase in b-wave amplitude in response to nylidrin or clenbuterol was observed for the cone systems. Both drugs also caused a reversible alteration in configuration of the optic nerve response, mainly a depression of the late components related in time to the changes in the electroretinogram. These observations suggest that beta-adrenergic mechanisms are involved in cone systems. The greater increase in b-wave amplitude on 558-nm stimulation and preliminary evidence for greater increase in sensitivity observed in the V-log I function compared with 439 nm further suggest that the short and long wavelength cone systems are affected differently by beta-adrenergic agonists.