Figure 3. Thrombin-induced glutamate release is mediated by PAR-1. Primary cultures of rat RPE cells were loaded with 1 µCi/ml ³H-glutamate and superfused with Krebs ringer bicarbonate (KRB; negative control) as described in Methods. Stimulation was carried in KRB containing increasing concentrations of thrombin (A) or of the specific protease-activated receptor 1 (PAR-1) agonist peptide Ser-Phe-Leu-Leu-Arg-Asn-amide trifluoroacetate salt (SFLLRN) (B), as described for Figure 2. Values are the mean ± standard error of the mean (SEM) of three independent experiments. The Student t test with respect to negative control was statistically significant (*p<0.05).