2024-03-29T14:19:11Z
https://niigata-u.repo.nii.ac.jp/oai
oai:niigata-u.repo.nii.ac.jp:00020821
2022-12-15T03:51:30Z
453:456
471:537:538:1171
A mechanism of contraction of the rat aortic smooth muscle by α_1-adrenoceptor stimulation : dependency on extracellular Na^+
アドレナリン作動性α_1-受容体刺激によるラット大動脈平滑筋の収縮 : 外液Na^+濃度依存性について
アドレナリン作動性α_1-受容体刺激によるラット大動脈平滑筋の収縮 : 外液Na^+濃度依存性について
水戸, 元子
128108
vascular smooth muscle
α_1-adrenoceptor
C-kinase
Na^+-H^+ exchange
Na^+-Ca^<2+> exchange
血管平滑筋
α_1-受容体
C-キナーゼ
Na^+-H^+交換機構
Na^+-Ca^<2+>交換機構
Contraction of rat aortic smooth muscle by α_1-adrenoceptor stimulation was examined in relation to extracellular Na^+ concentration. Experiments were carried out in the presence of verapamil (Ver) 10^<-5>M to avoid the contribution of Ca^<2+> influx via voltage dependent Ca^<2+> channel (VDC). The contraction induced by phenylephrine (Phe) 10^<-6>M under this condition depended on the presence of Ca^<2+> in the extracellular space, suggesting that the Ca^<2+> influx from the extracellular space was indispensable for elicitation of contraction. The contraction was also dependent on the concentration of Na^+ in the extracellular space except for Na^+-free condition. Tonic component of the contraction constitued a plateau with low Na^+ concentrations, but showed a gradual increase with time with higher Na^+ concentrations. Dichlorobenzamil, a Na^+-Ca^<2+> exchange system inhibitor, attenuated this contraction. Noradrenaline (Nor) 10^<-6>M also showed an extracellular Na^+ dependent contraction, as Phe did. However, in the absence of Na^+, almost equal contraction to those observed in the presence of normal concentration of Na^+ was observed, suggesting the contribution of Ca^<2+> release from intracellular Ca^<2+> store. The contraction by Nor as well as by Phe were inhibited by H-7, a C-kinase inhibitor. These results suggest that, when α_1-adrenoceptor is stimulated, C-kinase is activated through formation of diacylglycerol and increases in Na^+ influx via Na^+-H^+ exchange system results. The accumulated Na^+, in turn, enhances Na^+-Ca^<2+> exchange leading to increases in Ca^<2+> influx.
departmental bulletin paper
新潟医学会
1992-08
application/pdf
新潟医学会雑誌
8
106
787
795
新潟医学会雑誌
AN00182415
00290440
https://niigata-u.repo.nii.ac.jp/record/20821/files/106(08)_787-795.pdf
jpn