RT-PCR microlocalization of bradykinin B2 receptor mRNA in microdissected rat nephron segments.

Microlocalization of mRNA coding for the bradykinin 2 (BK2) receptor was carried out in the rat kidney. We combined reverse transcription and polymerase chain reaction (RT-PCR) with microdissection of individual renal tubule segments. Relative quantitation of the resulting amplified cDNA utilized densitometry of autoradiograms from Southern blots probed with a specific 32P 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 expression was also detected in the glomerulus, inner medullary thin limb (IMTL) and in the distal tubule (DT). Small but detectable signals were founded in the medullary thick ascending limb (MTAL). This distribution is consistent with multiple sites of BK action to account for different renal effects such as hemodynamics, water and electrolytic balance regulations.