Effect of captopril or verapamil on intracellular sodium in cultured vascular smooth muscle cells

The effects of captopril (Cap) and verapamil (Ver)alone and in combination on intracellular Na+ concentration ([Na+]i) in cultured aortic smooth muscle cells (ASMC) of rabbits was evaluated by a direct measurement of [Na+]i with fluorescent dye sodium-binding benzofuran isophthalate (SBFI) combined with digital image. [Na+]i in resting cells was found to be 11.9 ± 0. 7 mmol/L. Angiotensin II (Ang-II, 0.1-10μmol/L) induced an increase of [Na+]i in concentration-dependent manner. Ver (0.1-10μmol/L) inhibited Ang-II (1 μmol/L)-induced increase in [Na+]i, while Cap enhanced Ang-II-induced increase in [Na+]i at 10μmol/L but not at 0.1-1μmol/L. Ver (0.1-1μmol/L)abolished enhancement of Ang-II-induced increase in [Na+]i by Cap. Thus, the inhibition of Capenhanced [Na+]i by Ver may provide a new hypothesis for the underlying molecular mechanism of synergistic effect of the combination of Ca2+ antagonists and angiotensinconverting enzyme inhibitors in controlling blood pressure.

AIRWAY SMOOTH MUSCLE CELLS CULTURE AND APPLYING PERSPECTIVES

In order to study the physiological or pathophysiological responsiveness, airway smooth muscle cells were isolated from the rat trachea and cultured. The tracheas of adult rats were obtained by autopsy within 30 minutes after death and placed into a modified Hank’s solution. The experiments were performed on the large branches of the rat bronchi following entry into the lung. At the terminal level of the airway, no cartilage segments were seen. The muscle layer was prepared by careful removal of the connective tissue, cut into small pieces (1 mm3), and dispersed enzymatically (collagenase, elastase) into single cells. Freshly isolated cells could be used the same day. The small muscle pieces and isolated cells were cultured in the modified Hank’s or modified Eagle’s medium with 5% CO2 at 37℃ .

SHORT COMMUNICATIONS Comparison of inositol phosphates formation and gene expression of Gq alpha subunit in cultured aortic smooth muscle cells from spontaneously hypertensive and Wistar Kyoto rats

Abstract Objecitve To explore whether phosphoinositide specific phospholipase C (PLC) activation via G protein in vascular smooth muscle cells (VSMCs) is altered in spontaneously hypertensive rats (SHR). Methods The VSMCs derived from aortae of SHR and Wistar Kyoto (WKY) rats were loaded for 48 hours with myo inositol. Inositol phosphate release was initiated by the addition of 10 5 mol/L norepinephrine in intact cells or by guanosine 5' 0 (3 thio tri sphosphate) (GTP gamma S) in permeabilized cells. In the meantime, growth arrested VSMCs were stimulated by 10% calf serum for 0, 30, 45, or 60 min, then gene expressions of Gq alpha subunit (G alph a q) were observed. Results There were no significant differences in inositol 1, 4,5 triphosphate (IP 3) level and expression of G alpha q mRNA between quiescent VSMCs from SHR and that from WKY. When stimulated by norepinephrine, IP 3 production increased transiently with a peak level at 10 s in VSMCs from WKY, and a rapid biphasic IP 3 response, which was significantly higher than that of WKY, in VSMCs from SHR had been observed. G proteins activated by GTP gamma S significantly raised IP 3 production in VSMCs from SHR compared to WKY (SHR vs WKY: 234.8%±29.2% vs 142.4%±12.0% of basal IP 3, P<0.05). In addition, the serum effect showed an significant increase in expression of G alpha q mRNA in VSMCs from SHR. Conclusions The hereditary factors are not the only variable regulating IP 3 metabolism and G alpha q gene expression. Influences of multi environmental factors such as vasoactive compounds, together with genetic predisposition, palys an important role in the highly sensitive response of IP 3 production and G alpha q gene over expression in SHR.