Figure 4.

Cumulative concentration-effect curves for the relaxation of rings of canine basilar artery produced by the aminoglycosides. The preparations were first exposed to ET-1 (0.5 nM) (a) or PMA (160 nM) (b) and the aminoglycosides, gentamicin (genta), neomycin (neo), kanamycin (kana) and streptomycin (strepto), were administered in increasing cumulative concentrations to preparations in which maximum tonic tension had developed. Ordinate: relaxation expressed as a percentage of the maximum tension induced by ET-1. Abscissa: concentration of the aminoglycosides on a logarithmic scale. Data points represent the means±s.e.mean for experiments conducted with five or more ring preparations from three or more animals.