Experimental Study On The Effects Of Acute Pneumonia On Juvenile Rats'Right Ventricular L-type Ca～(2+) Currents And Intracellular Ca～(2+) Contents

Background and Objective: Infantile pneumonia remains one of the main causes of children's death in China. Several systems and organs may be injured during pneumonia, including the cardiovascular system. And cardiomyocyte is especially vulnerable to pneumonia. The disfunction of the heart would seriously affect the prognosis of pneumonia,especially a severe one. Anoxia, myocardial invoNment in infection, metabolic disturbance of the body and disorder of some humor factors such as oxygen free radical, endothelin, may all lead to the advent of heart failure due to pneumonia. The mechanism on the cellular scale, however, still remains unclarified. As it is known, calcium ion is not only the important "second messenger"for cellular signal transduction, but regarding myocytes a key factor in adjustment to contraction and relaxation. So myocardial L-type calcium current, and intracellular calcium ion content as well, are to be measured for the aim of probing the myocardial calcium metabolism alteration during pneumonia, to fu]f ii the utmost goal of unveil the possible mechanisms of the occurrence of heart failure due to pneumonia. Method and results: 50-day old Wister rats were given via trachea staphylococci aureus administration to build a pneumonic junvenile rat model. Single right ventricular myocytes were acquired by way of enzyrnatical isolation which was achieved with aortic retrograde perfusion on a brief langendoff apparatus under conditions of 3TC, pH7.3-7.4 and being oxygenated. On thu hasis of the above protocol, pneumonic groups of different disease stages and their control(s) were established for different experimental goals, namely, cross-membrane L-type Ca2+ eurrents(L) and intracellular Ca contents. 1. In experiment 1, four groups were established: a pneumonic group 24 hours after inoculation(pneumonic group 1), another one 120 after inoculation (pneumonic group 2), and two control groups (control group 1 and control group 2) which were set up by injecting the same amount of sterile normal saline in the same way i.e. via trachea, corresponding in time point respectively to the above pneumonic groups. The whole-cell clamp technique was employed to record L-type Ca2+ currents. Maximum currents, peak potentials and activation potentials were determinated and compared between pneumonic groups and their groups. 2. In experiment 2, three groups were established: a pneumonic group 21 hours after inoculation, another one 72 after inoculation, and a control group without any kind of administration. An adherent cell analysis and sorting cytometer 570 (ACAS 570) and fluo-3-AM, a Ca2+-specific fJ Llorescent probe were adopted to have a better understanding of effects oF dilThrent pneumonic stages on myocardial intracellular Ca2+ contents. Results: 1. The effect of pneumonia on right ventricular myocardial I~L Peak potentials and activation potentials kept OmV and -3OmV respectively. There is not a significant difference in maximum currents between pneumonic group 1 and control group 1 (P=0.410), but there is a significant one between pneumonic group 2 and control group 2(P<0. 001), that is, the maximum currents of pneumonic group 2 gained a prominent promotion. 2. The effect of pneumoni...