TAP1 I333V gene polymorphism and type 1 diabetes mellitus: a meta-analysis of 2248 cases.

Transporter associated with antigen processing 1 (TAP1) I333V gene polymorphism has been suggested to be associated with type 1 diabetes mellitus (T1DM) susceptibility. However, the results from individual studies are inconsistent. To explore the association of TAP1 I333V gene polymorphisms with T1DM, a meta-analysis involving 2246 cases from 13 individual studies was conducted. The pooled odd ratios (ORs) and their corresponding 95% confidence intervals (95% CIs) were evaluated by a fixed-effect model. A significant relationship was observed between TAP1 I333V gene polymorphism and T1DM in allelic (OR: 1.35, 95% CI: 1.08-1.68, P = 0.007), dominant (OR: 1.462, 95% CI: 1.094-1.955, P = 0.010), homozygous (OR: 1.725, 95% CI: 1.082-2.752, P = 0.022), heterozygous (OR: 1.430, 95% CI: 1.048-1.951, P = 0.024) and additive (OR: 1.348, 95% CI: 1.084-1.676, P = 0.007) genetic models. No significant association between TAP1 I333V gene polymorphism and T1DM was detected in a recessive genetic model (OR: 1.384, 95% CI: 0.743-2.579, P = 0.306) in the entire population, especially among Caucasians. No significant association between them was found in an Asian or African population. TAP1 I333V gene polymorphism was significantly associated with increased T1DM risk. V allele carriers might be predisposed to T1DM susceptibility.

Adrenergic regulation of the rapid component of delayed rectifier K+ currents in guinea pig cardiomyocytes.

BACKGROUND: Guinea pig ventricular cardiomyocytes display the rapid component of the delayed rectifier potassium current (Ikr) that contributes to ventricular repolarization and promotes stress-induced arrhythmias. Adrenergic stimulation favors ventricular arrhythmogenesis but its effects on Ikr are poorly understood. METHODS: Adrenergic modulation of Ikr was studied in isolated guinea pig ventricular cardiomyocytes using whole-cell patch clamping. RESULTS: We found that the Ikr amplitude was reduced to 0.66±0.02 and 0.62±0.03 in response to 0.1 µM phenylephrine (PE), an α1AR agonist, and 10 µM isoproterenol (ISO), a ßAR agonist, respectively. The effect of PE can be blocked by the selective α1A-adrenoceptor antagonist 5-methylurapidil, but not by the α1B-adrenoceptor antagonist chloroethylclonidine or α1D-adrenoceptor antagonist BMY7378. Additionally, the effect of ISO can be blocked by the ß1-selective AR antagonist CGP-20712A, but not by the ß2-selective AR antagonist ICI-118551. Although PE and ISO was continuously added to cells, ISO did not decrease the current to a greater extent when cells were first given PE. In addition, PE's effect on Ikr was suppressed by ß1AR stimulation. CONCLUSIONS: Ikr can by regulated by both the α1 and ß ARs system, and that in addition to direct regulation by each receptor system, crosstalk may exist between the two systems.