Expression and cellular localization of tissue kallikrein-kinin system in human adrenal gland.

The tissue kallikrein-kinin system has been implicated in regulating blood pressure and electrolyte homeostasis. To understand the function of this system, we identified the expression and cellular localization of its components including tissue kallikrein, kallistatin, kininogen, and bradykinin B1 and B2 receptors in human adrenal gland. Reverse transcription-polymerase chain reaction followed by Southern blot analysis showed that these five components of this system were all expressed in human adrenal gland. In situ hybridization histochemistry with respective digoxigenin-labeled antisense riboprobes revealed localization of kallikrein transcript throughout the adrenal cortex and medulla except the zona glomerulosa, whereas kallistatin mRNA was only localized in the zona fasciculata. Low-molecular-weight kininogen and B2 receptor mRNAs were colocalized in the zona glomerulosa and zona fasciculata and also in the zona reticularis and chromaffin cells but to a lesser degree. The B1 receptor mRNA was stained in the zona fasciculata and medulla. These results show the expression and differential colocalization of the components of the tissue kallikrein-kinin system and reveal the potential action sites of this system in the adrenal gland.