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Generation of the Action Potential
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
The independence of the Na+ and K+ voltage-gated channels is strongly supported by the fact that different drugs can selectively block one channel and not the other. Thus, the voltage-gated Na+ channel of neurons is selectively blocked by tetrodotoxin (TTX), a potent toxin produced by symbiotic bacteria and found in many animal species, particularly aquatic animals such as the puffer fish. Local anesthetics, such as procaine, are synthetic drugs that, by blocking the voltage-gated Na+ channels of axons carrying pain signals, prevent pain-induced APs in the periphery from reaching the central nervous system and hence the brain centers responsible for the sensation of pain. The voltage-gated K+ channel in axons is selectively blocked by the synthetic drug tetraethylammonium (TEA).
Advances in the synthesis and chemical transformations of 5-acetyl-1,3,4-thiadiazolines
Published in Journal of Sulfur Chemistry, 2021
Samir Bondock, Tallah Albarqi, Mohamed Abboud
It has been reported that the reaction of 3-oxo-3-(piperidin-1-yl)propanenitrile (24) with phenyl isothiocyanate (9) in a basic medium furnished the non-isolable potassium salt 25 which reacts in situ with the appropriate hydrazonoyl chlorides 1a,b,d,g to produce 5-acetyl-2,3-dihydro-1,3,4-thiadiazole derivatives 28a–d. The authors proposed that the reaction starts with the nucleophilic substitution of chlorine atom by thiolate ion to afford the intermediate 26 which subsequently undergoes cyclization via loss of a molecule of aniline as depicted in Scheme 7 [30]. Noteworthy, compounds 28a–d have displayed higher anti-arrhythmic activity than the reference procaine amide and/or lidocaine drugs. Compound 28c having chlorine atom exhibited high potent anti-arrhythmic activity with value of acute toxicity (LD50 = 654.11 ± 1.18 mg/kg).