Interleukin-2 altered the frequency -dependent relationship of intracellular calcium in rat ventricular myocytes / 中国病理生理杂志

AIM: We examined the effect of interleukin- 2 (IL-2) on calcium handlin g of rat cardiomyocytes. METHODS: The effects of steady state an d transient chan ges in stimulus frequency on the intracellular calcium transient were investigat ed in the isolated ventricular myocytes with spectrofluorometry technique. RESULTS: Under the steady state (0.2 Hz), IL-2 at 2?10 5 U/L decr eased the peak [Ca 2+ ] i and amplitude of the [Ca 2+ ] i transient, increas ed the diastolic calcium level, and prolonged the decay of the calcium transient . At 1.25 mmol/L of extracellular [Ca 2+ ], when increasing the stimulus frequency from 0.2 to 1.0 Hz, diastolic calcium level and peak [Ca 2+ ] i as well as the amplitude of the transient were inc reased. The positive frequency relationship was blunted in the IL-2-treated myoc ytes and this was not normalized by increasing extracellular [Ca 2+ ] t o 2.5 mmol/L . The caffeine induced Ca 2+ release was increased with increase in stimu lus freq uency. IL-2 inhibited the frequency relationship of caffeine induced Ca 2+ releas e. The restitution was not different between control and IL-2 groups at the 1.25 mmol/L of extracellular [Ca 2+ ], which was slowed in IL-2-treated myo cytes when t he extracellular [Ca 2+ ] was increased to 2.5 mmol/L. CONCLUSIO NS: It is concluded that the blunted frequency response of IL-2-treated myocytes was resulted from the decrease in SR Ca 2+ release, which was related to depression of SR funct ion. Despite the evidence of depressed SR Ca 2+ uptake, the restitution o f ca lcium transient at 1.25 mmol/L of extracellular [Ca 2+ ] remains uncha nged, which maybe due to the increase in the Na +/Ca 2+ exchanger activi ty.

Changes of NO concentrations of different tissues and blood pressure in stress rats / 中国临床药理学与治疗学

AIM: To study the changes of NO concentrations of different ti ssues in stress rats. METHODS: Add stimulation with experiments employed electric food-shock and noise of busser as stressor for 15 days in SD rats,NO concentrations and BP were measured. RESULTS: In stress group, BPs increased before and after stress stimulation,but decreased levels NO concentrations of plasma, and there was no detectable amounts of NO in auricl e, ventricle, vessel and adrenal. In stress +L-arg group, BPs d id not increase before and after stress stimulation, NO concentrations of plasma increased, but auricle, ventricle, vessel and adrenal maintained the concentrat ions of NO. CONCLUSION: The stress stimulation can increase BP a nd low NO concentration, and L-arg can resist the response.