Which drug with cardiorespiratory stimulant effects, has been demonstrated to reverse diaphgramatic blockade, bradypnea and bradycardia in a guinnea pig model of saxitoxin and tetrodotoxin toxicity?
4-Aminopyridine. The proposed mechanism is intracellular potassium channel blockade resulting in greater than normal calcium influx in presynaptic nerve terminals and thereby enhanced Acetylcholine release. (Chen, Hsing-Ming, et al. “Effects of 4-Aminopyridine on Saxitoxin Intoxication.” Toxicology and Applied Pharmacology, vol. 141, no. 1, 1996, pp. 44–48., doi:10.1016/s0041-008x(96)80007-x.)