Yarbrough G G, McGuffin-Clineschmidt J C
Eur J Pharmacol. 1979 Nov 23;60(1):41-6. doi: 10.1016/0014-2999(79)90050-5.
Administered by either intravenous (i.v.) or intracisternal (i.cis.) injections, MK-771 and TRH induced a dose-related increase in EMG activity recorded from the flexor ulnaris muscle in pentobarbital-anesthetized rats. By the i.v. route, MK-771 was 6 times more potent than TRH and with i.cis. administration MK-771 was some 30 times more active than TRH. At equieffective doses of the two peptides, MK-771 exhibited a greater (approximately 3 fold) duration of action than TRH. In unanesthetized, spinally transected rats MK-771 was also more potent than TRH in eliciting EMG activity recorded from the biceps femoris muscle. Substance P, administered by the i.cis route failed to induce EMG activity. Intracisternally administered neurotensin, which did not affect EMG activity by itself, antagonized the actions of MK-771 while somatostatin was inactive in this regard. Neurotensin did not affect the EMG activity induced by physostigmine. While these studies do not delineate the mechanism whereby TRH and MK-771 induce EMG activity, it appears reasonable to suggest that TRH and related peptides, such as MK-771, may have some influence in functional disorders of human muscle.
通过静脉注射（i.v.）或脑池内注射（i.cis.）给予MK - 771和促甲状腺激素释放激素（TRH），在戊巴比妥麻醉的大鼠中，尺侧腕屈肌记录到的肌电图（EMG）活动呈现剂量相关的增加。通过静脉注射途径，MK - 771的效力比TRH高6倍，而通过脑池内给药，MK - 771的活性比TRH高约30倍。在两种肽的等效剂量下，MK - 771的作用持续时间比TRH更长（约3倍）。在未麻醉、脊髓横断的大鼠中，MK - 771在诱发股二头肌记录到的EMG活动方面也比TRH更有效。通过脑池内途径给予的P物质未能诱发EMG活动。脑池内给予的神经降压素本身不影响EMG活动，但拮抗MK - 771的作用，而生长抑素在这方面无活性。神经降压素不影响毒扁豆碱诱导的EMG活动。虽然这些研究没有阐明TRH和MK - 771诱发EMG活动的机制，但有理由认为TRH和相关肽，如MK - 771，可能对人类肌肉的功能障碍有一定影响。
