|Budget Amount *help
¥1,700,000 (Direct Cost : ¥1,700,000)
Fiscal Year 1994 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1993 : ¥900,000 (Direct Cost : ¥900,000)
The purpose of this research is to investigate the mechanisms of abnormal regulation of vascular contraction and cell proliferation in diabetes mellitus. The following results were obtained :
1.CELL PROLIFERATION OF VASCULAR SMOOTH MUSCLE CELLS.I developed the method to determine the phase of the cell cycle of vascular smooth muscle cells in primary culture at the single cell level. It was found that : (1)cytosolic Ca^<2+> transients are not required for platelet-derived growth factor (PDGF) to stimulate the cell cycle progression from the G_0 phase to the G_1 phase ; and (2)high glucose does not stimulate the cell cycle of the G_0 cells, whereas it stimulates the cell cycle of the PDGF-pretreated G_1 cells to the S and M phases, without any increase of cytosolic Ca^<2+> concentration ([Ca^<2+>]i).
2.CALCIUM TRANSIENTS OF ENDOTHELIAL CELLS.Using front-surface fluorometry and fura-2-loaded valvular endothelial cells in situ, it was found that : (1)endothelin-1 (ET-1) elevates [Ca^<2+>]i b
y the stimulation of both Ca^<2+> influx and intracellular Ca^<2+> release ; and 2)the Ca^<2+>influx is regulated by an pertussis toxin-sensitive G-protein, while the release of intracellular Ca^<2+> is not.
3.VASCULAR CONTRACTION.(1)Using RT-PCR and fura-2 microfluorometry, it was found that angiotensin II (AT-II), protein kinase C,and protein Kinase A regulate the expression of AT-II receptor mRNA,and the increase in mRNA level is accompanied by an increase in physiological responsiveness. (2) Using fura-2-front-surface fluorometry and porcine coronary arterial strips, it was found that ET-3 induced vasoconstriction by increasing [Ca^<2+>]i mainly through the influx of extracellular Ca^<2+>, and that distinct mechanisms of time-dependent modulation of the Ca^<2+>-sensitivity function in the vasoconstrictor responses to ET-1 and ET-3. (3)It was found that norepinephrine induced increase in the Ca^<2+>-sensitivity of contractile apparatus, while serotonin demonstrates little enhancement of the Ca^<2+>-sensitivity of contractile apparatus. Less