Expression of kininogen genes by rat cardiomyocytes

To determine the existence of the kallikrein-kinin system in the heart, we have studied in vitro and in vivo whether rat heart expresses kininogens (K GNs). The reverse transcription-polymerase chain reaction (RT-PCR) for KGN mRNAs demonstrated that the cardiac tissue of adult male rats expresses T-K GN mRNA but not high-molecular-weight (H-) KGN mRNA. An intravenous injecti on of lipopolysaccharide (LPS) resulted in a significant increase in T-KGN mRNA levels of rat heart within 12 h. Polyacrylamide gel electrophoresis of cDNA products generated by RT-PCR from heart mRNA using primers specific f or either T- or low-molecular-weigh (L-) KGN revealed that rat heart expres sed not only T-KGN gene but also L-KGN gene, and that LPS injection exclusi vely stimulated the expression of T-KGN but not of L-KGN gene. T-KGN mRNA w as also detected in cultured myocytes derived from fetal rat heart, and the expression was markedly enhanced by an addition of LPS to cultures. These results demonstrated that rat cardiomyocytes are the source of T- and L-KGN s but not of H-KGN, and that their expression of T-KGN mRNA is stimulated b y LPS, probably via LPS-receptor CD14. (C) 1999 Elsevier Science B.V. All r ights reserved.