DYSFUNCTION OF MYOCARDIAL AND VASCULAR TAURINE TRANSPORT IN L-N~ω-NITRO-ARGININE-INDUCED HYPERTENSIVE RATS

摘要

Objective. To study the change of taurine transport, and taurine transporter (TAUT) and cysteine sulfinate decarboxylase (CSD) mRNA contents in hypertension and hypertensive cardiomegaly. Methods. Taurine content was determined with a amino acid analyser. Taurine uptakes were determined by (~3H)-taurine incubation. The content of TAUT and CSD mRNA levels were measured by competitive quantitative RT-PCR in myocardial and vascular tissues of L-N~ω-nitro-arginine (L-NNA)-induced hypertensive rats. Results. After the treatment of rats with L-NNA for 28 days, myocardial and vascular taurine contents decreased by 11% and 15% (P<0.05), respectively, and plasma taurine level increased by 13% (P<0.05). Myocardial and vascular Vmax of taurine uptake reduced by 30% and 19% (P<0.05), respectively. Their Km of taurine uptake increased by 36% and 17% (P<0.05). Myocardial and vascular TAUT mRNA content decreased by 22% and 19% (P<0.05), respectively, but CSD mRNA content increased by 22% (P<0.05) and 30% (P<0.01), respectively. Conclusions. This study suggests that there is a decreased taurine content in myocardial and vascular tissues of L-NNA-induced hypertension rats. The decreased taurine content may result from the decreased number of TAUT on the cell membrane mainly due to the down-regulation of TAUT gene and TAUT affinity caused by hypertension and hypertensive cardiomegaly.