초록
There have been conflicting reports concerning the effect of Panax ginseng on the contractility of vascular smooth muscle, i.e., Panax ginseng extract has been reported to cause relaxation, contraction or to have no effect on the tension of vascular smooth muscle. A further investigation of $Ca^{++}$ stores which supply $Ca^{++}$ for contraction of vascular smooth muscle is needed to understand the underlying mechanisms of this conflicting effect of ginseng alcohol extract (GAE). The present study was intended to examine the sources of calcium mobilized for contraction of vascular smooth muscle by GAE. Aortic ring preparations were made from the rabbit thoracic aorta and endothelial cells were removed from the ring. The contractility of the aortic ring was measured under various experimental conditions and $Ca^{++}$ flux across the membrane of aortic ring and the sarcoplasmic reticulum and mitochondria were measured with a calcium selective electrode. The result were summarized as follows; 1) At low concentration of extracellular $Ca^{++}$, GAE increased the contractility of vascular smooth muscle in dose-dependent fashion except high concentration $Ca^{++}$ (1 mM). 2) In the presence of ryanodine, GAE still increased contractility of vascular smooth muscle as much as control group, but in the presence of caffeine, GAE increased it significantly. i.e. Their effects seemed to be additive. 3) In the presence of verapamil+lanthanum, and verapamil+lanthanum+ryanodine, the contractility of the vascular smooth muscle was decreased, but a dose dependent increase in vascular tension was still demonstrated by GAE although total tension was low. 4) GAE increased $Ca^{++}$ efflux from vascular smooth muscle cells, but have no effect on $Ca^{++}$ influx. 5) GAE increased $Ca^{++}$ efflux from sarcoplasmic reticulum and mitochondria vesicles. From the above results, it may be concluded that GAE increased the release of $Ca^{++}$ from sarcoplasmic reticulum, mitochondria or other intracellular $Ca^{++}$ stores of vascular smooth muscle, but it does not increase $Ca^{++}$ influx across the plasma membrane.