Dysfunction of myocardial taurine transport and effect of taurine supplement in rats with isoproterenol-induced myocardial injury.
Abstract
AIM: To study the alterations of myocardial taurine transport function, taurine
transporter (TAUT), and cysteine sulfinate decarboxylase (CSD) mRNA as well as
effect of exogenous taurine in rats with isoproterenol (ISO)-induced
cardiomegaly.
METHODS: [3H]-Taurine uptake and release on myocardium were determined. Binding
sites of [3H]-taurine for myocardial sarcolemma were measured. TAUT and CSD mRNA
levels were assayed using competitive quantitative reverse transcriptase
polymerase chain reaction (RT-PCR).
RESULTS: ISO group as compared with control group, myocardial taurine uptake
markedly reduced, taurine release obviously increased; Bmax value of [3H]-taurine
binding on cardiac sarcolemma reduced by 42% (P<0.05); TAUT and CSD mRNA levels
decreased by 40% and 38% (P<0.05), respectively. ISO+taurine group as compared
with ISO-treated group, the amounts of taurine uptake and TAUT mRNA returned to
normal; taurine release reduced; Bmax increased by 92% (P<0.01), and CSD mRNA
content augmented by 23% (P<0.05). There were no statistical differences of Kd
values among the four groups (P>0.05).
CONCLUSION: The data indicate that the failure to generate sufficient TAUT on
myocardial sarcolemma may be the fundamental abnormality in ISO-induced cardiac
injury. The mechanism by which administration of taurine considerably improves
ISO-induced cardiac damage is probably to increase the expression of TAUT gene
and recover taurine transport function.
Keywords:
transporter (TAUT), and cysteine sulfinate decarboxylase (CSD) mRNA as well as
effect of exogenous taurine in rats with isoproterenol (ISO)-induced
cardiomegaly.
METHODS: [3H]-Taurine uptake and release on myocardium were determined. Binding
sites of [3H]-taurine for myocardial sarcolemma were measured. TAUT and CSD mRNA
levels were assayed using competitive quantitative reverse transcriptase
polymerase chain reaction (RT-PCR).
RESULTS: ISO group as compared with control group, myocardial taurine uptake
markedly reduced, taurine release obviously increased; Bmax value of [3H]-taurine
binding on cardiac sarcolemma reduced by 42% (P<0.05); TAUT and CSD mRNA levels
decreased by 40% and 38% (P<0.05), respectively. ISO+taurine group as compared
with ISO-treated group, the amounts of taurine uptake and TAUT mRNA returned to
normal; taurine release reduced; Bmax increased by 92% (P<0.01), and CSD mRNA
content augmented by 23% (P<0.05). There were no statistical differences of Kd
values among the four groups (P>0.05).
CONCLUSION: The data indicate that the failure to generate sufficient TAUT on
myocardial sarcolemma may be the fundamental abnormality in ISO-induced cardiac
injury. The mechanism by which administration of taurine considerably improves
ISO-induced cardiac damage is probably to increase the expression of TAUT gene
and recover taurine transport function.