Analysis of the responses of frog motoneurons to epinephrine and norepinephrine.
Epinephrine and norepinephrine were applied to the isolated superfused frog spinal cord hyperpolarized motoneurons. The hyperpolarization was related to both direct and indirect actions and the indirect effects were produced by activation of alpha 2-adrenoceptors. In about half of the spinal cords a slow depolarization caused by activation of beta-receptors was seen and was largely attributable to direct actions of the catecholamines on motoneuron membranes. In a small number of preparations an early alpha 1-mediated depolarization was noted. The results suggest that catecholamines released from terminals in the frog ventral horn could exert a modulatory action on the motoneuron output from the spinal cord.
D018674:Adrenergic Antagonists; D000663:Amphibians; D000818:Animals; D004837:Epinephrine / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D009046:Motor Neurons / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology*; D011941:Receptors, Adrenergic / Q000145:classification / Q000187:drug effects; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D018674:Adrenergic Antagonists; D011941:Receptors, Adrenergic; D009638:Norepinephrine; D004837:Epinephrine