RT-PCR analysis of dopamine D
-like receptors in human airway smooth muscle. Representative gel images of RT-PCR analysis of total RNA using primers specific for human dopamine D1 receptor (A) and D5 receptor (B). Total RNA extracted from freshly dissected human tracheal airway smooth muscle or primary cultures of human airway smooth muscle (HASM) cells was analyzed. Lanes 1: base pair standards; Lanes 2: negative control (no RNA); Lanes 3: total RNA from freshly dissected native human airway smooth muscle tissue; Lanes 4: total RNA from primary cultured HASM cells obtained from Lonza (Walkersville, MD); Lanes 5: total RNA from whole human brain. −RT; cDNA synthesis reactions performed in the absence of reverse transcriptase confirming that PCR products were not arising from contaminating genomic DNA.