Abstract
1 Effects of 4-aminopyridine (4-AP) and tetraethylammonium (TEA) on the neuro-effector junction of the guinea-pig vas deferens were investigated by microelectrode and double sucrose gap techniques. 2 4-AP (0.05 to 0.5 mM) or TEA (0.5 to 1 mM) did not alter the membrane potential, or the membrane input resistance of the smooth muscle cell. 3 The amplitude and frequency of the miniature junction potentials (m.e.j.ps) were not modified by treatment with 4-AP (0.05 to 0.5 mM) or TEA (1 mM). 4 4-AP (1 mM) increased the membrane input resistance, enhanced the spike amplitude of the smooth muscle cells and thereby augmented the amplitude of twitch contraction. 5 4-AP (.05 to 0.5 mM) or TEA (1 mM) markedly increased the amplitude of excitatory junction potentials (e.j.ps), but the facilitation phenomena produced by repetitive stimulation were not affected. 6 The duration of the extracellularly recorded action potential from the small nerve bundle was prolonged by 4-AP (0.5 mM). 7 The amplitude of the e.j.p. was dependent on the external concentration of calcium. A straight line was produced when the amplitude of the e.j.p. and [Ca]o was plotted on a double log scale. Application of 4-AP resulted in a parallel shift of this line to the left. 8 These results indicate that 4-AP (0.05 to 0.5 mM) and TEA (0.5 to 1.0 mM) prolonged the action potential generated from the sympathetic nerve terminal thus enhancing the amplitude of the e.j.p. due to an increase in the Ca-influx. However, in the concentrations used, these compounds did not modify the Ca-mobilization in the nerve terminal or the postsynaptic membrane during the resting state.
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- Beaulieu G., Frank G. B. Tetraethylammonium-induced contractions of frog's skeletal muscle. 3. Mechanism of action by calcium release. Can J Physiol Pharmacol. 1967 Sep;45(5):845–855. doi: 10.1139/y67-099. [DOI] [PubMed] [Google Scholar]
- Illes P., Thesleff S. 4-Aminopyridine and evoked transmitter release from motor nerve endings. Br J Pharmacol. 1978 Dec;64(4):623–629. doi: 10.1111/j.1476-5381.1978.tb17325.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ito Y., Kuriyama H., Sakamoto Y. Effects of tetraethylammonium chloride on the membrane activity of guinea-pig stomach smooth muscle. J Physiol. 1970 Dec;211(2):445–460. doi: 10.1113/jphysiol.1970.sp009286. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ito Y., Suzuki H., Kuriyama H. On the roles of calcium ion during potassium induced contracture in the smooth muscle cells of the rabbit main pulmonary artery. Jpn J Physiol. 1977;27(6):755–770. doi: 10.2170/jjphysiol.27.755. [DOI] [PubMed] [Google Scholar]
- Ito Y., Tajima K. An electrophysiological analysis of the actions of prostaglandin on neuromuscular transmission in the guinea-pig vas deferens. J Physiol. 1979 Dec;297(0):521–537. doi: 10.1113/jphysiol.1979.sp013054. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Johns A., Golko D. S., Lauzon P. A., Paton D. M. The potentiating effects of 4-aminopyridine on adrenergic transmission in the rabbit vas deferens. Eur J Pharmacol. 1976 Jul;38(1):71–78. doi: 10.1016/0014-2999(76)90202-8. [DOI] [PubMed] [Google Scholar]
- KOKETSU K. Action of tetraethylammonium chloride on neuromuscular transmission in frogs. Am J Physiol. 1958 Apr;193(1):213–218. doi: 10.1152/ajplegacy.1958.193.1.213. [DOI] [PubMed] [Google Scholar]
- KURIYAMA H. EFFECT OF CALCIUM AND MAGNESIUM ON NEUROMUSCULAR TRANSMISSION IN THE HYPOGASTRIC NERVE-VAS DEFERENS PREPARATION OF THE GUINEA-PIG. J Physiol. 1964 Dec;175:211–230. doi: 10.1113/jphysiol.1964.sp007513. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kao C. Y., Stanfield P. R. Actions of some cations on the electrical properties and mechanical threshold of frog sartorius muscle fibers. J Gen Physiol. 1970 May;55(5):620–639. doi: 10.1085/jgp.55.5.620. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Katz B., Miledi R. Spontaneous and evoked activity of motor nerve endings in calcium Ringer. J Physiol. 1969 Aug;203(3):689–706. doi: 10.1113/jphysiol.1969.sp008887. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kirpekar M., Kirpekar S. M., Prat J. C. Effect of 4-aminopyridine on release of noradrenaline from the perfused cat spleen by nerve stimulation. J Physiol. 1977 Nov;272(3):517–528. doi: 10.1113/jphysiol.1977.sp012057. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kirpekar S. M., Wakade A. R., Prat J. C. Effect of tetraethylammonium and barium on the release of noradrenaline from the perfused cat spleen by nerve stimulation and potassium. Naunyn Schmiedebergs Arch Pharmacol. 1976 Jul;294(1):23–29. doi: 10.1007/BF00692781. [DOI] [PubMed] [Google Scholar]
- Lundh H., Leander S., Thesleff S. Antagonism of the paralysis produced by botulinum toxin in the rat. The effects of tetraethylammonium, guanidine and 4-aminopyridine. J Neurol Sci. 1977 May;32(1):29–43. doi: 10.1016/0022-510x(77)90037-5. [DOI] [PubMed] [Google Scholar]
- Lundh H., Thesleff S. The mode of action of 4-aminopyridine and guanidine on transmitter release from motor nerve terminals. Eur J Pharmacol. 1977 Apr 21;42(4):411–412. doi: 10.1016/0014-2999(77)90176-5. [DOI] [PubMed] [Google Scholar]
- Mallart A., Martin A. R. An analysis of facilitation of transmitter release at the neuromuscular junction of the frog. J Physiol. 1967 Dec;193(3):679–694. doi: 10.1113/jphysiol.1967.sp008388. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Miledi R., Thies R. Tetanic and post-tetanic rise in frequency of miniature end-plate potentials in low-calcium solutions. J Physiol. 1971 Jan;212(1):245–257. doi: 10.1113/jphysiol.1971.sp009320. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rougier O., Vassort G., Garnier D., Gargouil Y. M., Coraboeuf E. Existence and role of a slow inward current during the frog atrial action potential. Pflugers Arch. 1969;308(2):91–110. doi: 10.1007/BF00587018. [DOI] [PubMed] [Google Scholar]
- Thoenen H., Haefely W., Staehelin H. Potentiation by tetraethylammonium of the response of the cat spleen to postganglionic sympathetic nerve stimulation. J Pharmacol Exp Ther. 1967 Sep;157(3):532–540. [PubMed] [Google Scholar]
- Ulbricht W., Wagner H. H. Block of potassium channels of the nodal membrane by 4-aminopyridine and its partial removal on depolarization. Pflugers Arch. 1976 Nov 30;367(1):77–87. doi: 10.1007/BF00583659. [DOI] [PubMed] [Google Scholar]
- Yeh J. Z., Oxford G. S., Wu C. H., Narahashi T. Interactions of aminopyridines with potassium channels of squid axon membranes. Biophys J. 1976 Jan;16(1):77–81. doi: 10.1016/S0006-3495(76)85663-9. [DOI] [PMC free article] [PubMed] [Google Scholar]