RT-PCR MICROLOCALIZATION OF BRADYKININ B2 RECEPTOR MESSENGER-RNA IN MICRODISSECTED RAT NEPHRON SEGMENTS

Microlocalization of mRNA coding for the bradykinin 2 (BK2) receptor w as carried out in the rat kidney. We combined reverse transcription an d polymerase chain reaction (RT-PCR) with microdissection of individua l renal tubule segments. Relative quantitation of the resulting amplif ied cDNA utilized densitometry of autoradiograms from Southern blots p robed with a specific P-32 labeled probe. The largest signals for BK2 receptor PCR product were detected in the cortical collecting tubule ( CCT) and the proximal straight tubule (PST). BK2 receptor mRNA express ion was also detected in the glomerulus, inner medullary thin limb (IM TL) and in the distal tubule (DT). Small but detectable signals were f ounded in the medullary thick ascending limb (MTAL). This distribution is consistent with multiple sites of BK action to account for differe nt renal effects such as hemodynamics, water and electrolytic balance regulations.