Figure 3.

Detection of GABA_BR expressions and GABA_BR1 transcripts in heart and brain. (A) In whole-cell lysates of rat cardiomyocytes, AbC22 directed against GABA_BR2 coprecipitates GABA_BR1 detected on the immunoblot with Ab174.1 antibody (lane 1), whereas Ab174.1 directed against GABA_BR1 coprecipitates GABA_BR2 detected with AbC22 antibody (lane 2). IP, immunoprecipitation; WB, Western blot. Thin bars point to protein bands attributed to GABA_BR1 (R1) and GABA_BR2 (R2) subtypes. α-R1 and α-R2, antibodies directed against R1 and R2, respectively. In whole-cell lysates from hippocampal cells, immunoblots confirmed the presence of GABA_BR1a (R1a) and GABA_BR1b (R1b) isoforms (lane 3) and GABA_BR2 (lane 4) receptor. (B) Northern blot analysis of GABA_BR1a and -R1b transcripts in rat cardiomyocytes (Heart) and hippocampal tissue (Brain). Receptor mRNAs were amplified by RT-PCR, using primers specific to the different 5′ ends of the two isoforms, and the products were size fractionated on 2% agarose gels for comparison with a 100-bp DNA ladder (first lane). The expected product sizes for R1a and R1b isoforms were 524 and 426 bp, respectively. Each blot is representative of three experiments.