四、smooth muscle:relaxation characteristics 1)作用强度与SM紧张度成正比 对痉享的SM作用最强 2)selectivity to smooth muscle: gastrointestinal tract>urinary bladder,膀胧、 urethra尿道>Biliary tract胆管、ureter输尿 管、bronchia支气管、uterus子宫 characteristics 1) 作用强度与SM紧张度成正比 对痉挛的SM作用最强 2) selectivity to smooth muscle： gastrointestinal tract > urinary bladder膀胱、 urethra尿道 > Biliary tract 胆管、 ureter 输尿 管、bronchia支气管、uterus子宫 四、smooth muscle ：relaxation