Adrenergic control of tendon jerk reflexes in man.
1. Tendon jerk responses and H reflexes were recorded from conscious human volunteers before and after intravenous injection of methylamphetamine, thymoxamine and propranolol, and during intravenous infusion of noradrenaline.2. Methylamphetamine produced a significant increase in the amplitude of the tendon jerk, whereas noradrenaline had no effect in doses which caused a greater pressor response than methylamphetamine.3. Thymoxamine produced a dose-related reduction in the tendon jerk.4. Propranolol had no significant effect on the jerk.5. None of these drugs significantly affected the H reflex.6. It is suggested that central adrenoceptors, possibly alpha in type, exist in man, and that stimulation of these receptors facilitates tendon jerk reflexes by an action on the fusimotor system.
D001794:Blood Pressure / Q000187:drug effects; D004295:Dihydroxyphenylalanine / Q000494:pharmacology; D004558:Electric Stimulation; D004576:Electromyography; D006801:Humans; D008694:Methamphetamine / Q000494:pharmacology; D009046:Motor Neurons / Q000187:drug effects; D013948:Moxisylyte / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D012023:Reflex, Monosynaptic / Q000187:drug effects; D012026:Reflex, Stretch; D013564:Sympathetic Nervous System / Q000502:physiology*; D013997:Time Factors; D014159:Transducers
D008694:Methamphetamine; D004295:Dihydroxyphenylalanine; D011433:Propranolol; D013948:Moxisylyte; D009638:Norepinephrine; D010646:Phentolamine