Figure 6. ET-1, ETA-, and ETB-receptor mRNA are expressed in rat islets and rat beta-cell lines. RT-PCR from isolated total RNA from freshly isolated rat islets and rat beta-cell lines (INS-1, RINm5f) was performed with intron-spanning primers specific for ET-1 (727 bp), ETA- (546 bp), ETB-receptor (474 bp) and proinsulin (354 bp). For reference, a 100 bp-ladder DNA size marker is shown (arrow: 600 bp).