As a result there is no neuromusrulat bansmission (transmssion failure'or neuromuscular block) and warysis of the affected mus

development of depolarization. remains in a state of depolarization for a longer tirne During this stale, the muscle fiber although deplarized remains in a state of relaxation tocauss then is no bar to regan relation (which is a mechanic event) from contraction Or in other words, the muscle fiber is, in this phase, although in a relaxed state, is refractory to any stimulus (because it is in a depoliflztd state. to develop another twitch, the muscle must be repolaraed or reprimed' and then again depolarized) and hentce it is lated that succinyl choline causes neuromuscular block after an initial twich(Recalthat for each single contraction, an nedividual AP must develop) Such blocks are called depoarizing block 'succiny choling is used by the anesthesists as a muscle relaxant 2 Botuirum toxin This Toxin, obtained from the bacteia. Clauslriddum batult num. prevents the release of ACh from the nerve terminal As a result there is no neuromusrulat bansmission (transmssion failure'or neuromuscular block) and warysis of the affected must te occurs Bolulinurn toxin has agreat potential as a future chemical(blological) war weapon Only some 200gms of this toxin canape out an hirnan Iives from the earth The toxin can concervably be mated up with The nver water and thus trie devastations can be produced 3 Curare The deadly Souti American arrowhead poision, curare or its active printiple, d-tubocurarine (an alkaloid), can tombne with the motor end plat receptor but does not depolarize the post junctiona! membrane ( ie. acts an ACh receptor blocter) As it remains combined with the receptor, ACh molecules cannot combine, as the receptor surfac es are ailoctuped by the d-fubcurarine motecles and as a result. the normal neuromuscular transmission is blocked, death occurs due to respiratory pararyse (due to neuromuscular block setting In diaprhtagm and other respiritory mustlesj Curare and Tne related drugs are tierefort, calBd comcenve antagonsts d-rubocuianne may also be used as a muscle reiaxant in anesthesiology The drug gallamine also behaves like tubocurarine It should be understood that bebween some 75 to 90% or the receptor molecules must be blocked by tubocurarlne or galtamtne before neuromuscular blocking (an be ensured Bungaratoxin. a Chemical obtained from vernn of some species of deatly snakes, also combines with the receptor and this combination is irreversible Bungarotoxin is used extensively by experimental phyooiogiste/