Esterase vertebrates

A few OP compounds cause delayed neuropathy in vertebrates because they inhibit another esterase located in the nervous system, which has been termed neuropathy target esterase (NTE). This enzyme is described in Chapter 10, Section 10.2.4. OPs that cause delayed neuropathy include diisopropyl phosphofluoridate (DFP), mipafox, leptophos, methamidophos, and triorthocresol phosphate. The delay in the appearance of neurotoxic symptoms following exposure is associated with the aging process. In most cases, nerve degeneration is not seen with initial inhibition of the esterase but appears some 2-3 weeks after commencement of exposure, as the inhibited enzyme undergoes aging (see Section 16.4.1). The condition is described as OP-induced delayed neuropathy (OPIDN). 

Augustinsson, K-B. (1961). Multiple forms of esterase in vertebrate blood plasma. Ann. NY Acad. Sci. 94 844-60. 

The failure to find C02 In the expired air of the mice Indicates that the tropic acid moiety in the atropine molecule Is not metabollzed ln accord with the finding that labeled tropic acid Itself was excreted without loss In the urine. The finding of atropine but no tropic acid In the urine of the mice Indicates that hydrolysis of the ester did not occur rapidly. The latter finding was somewhat unexpected because an esterase capable of hydrolysing atropine is present In the livers of many vertebrate species, although It or a similar enzyme appears In the sera of only a few species (93-95). This enzyme Is also able to hydrolyze L hyoscyamine, troplnyl benzoate, and caramlphen (95). 

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