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HEPES(N-2-羟乙基哌嗪-W′-2-乙磺胺)是一个常用缓冲剂,通常认为除稳定pH 作用外,无其他药理活性。但最近Norris 等证明它可能具有抗胆碱作用。作者采用蛙离体半规管标本,研究胆碱能激动剂和拮抗剂对半规管壶腹神经传入神经元冲动发放率的影响。灌流液采用碳酸盐作缓冲剂时,乙酰胆碱对神经元冲动发放率可产生兴奋和抑制的双向作用。但采用HEPES 作缓冲剂时,乙酰胆碱只产生抑制作用,这种
HEPES (N-2-hydroxyethylpiperazine-W’-2-ethanesulfonamide) is a commonly used buffering agent and is generally considered to have no other pharmacological activity other than its ability to stabilize pH. However, Norris et al recently demonstrated that it may have anticholinergic effects. The authors used frog semicircular canal specimens in vitro to study the effects of cholinergic and antagonistic agents on the rate of impulsive afferent neurons in the ampulla of the semicircular canal. When carbonate is used as a buffer in the perfusate, acetylcholine exerts a bidirectional effect of excitement and inhibition on the rate of neuron impulse delivery. However, the use of HEPES as a buffer, acetylcholine only produce inhibition, this