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PILOCARPINE‐INDUCED SUBSENSITIVITY TO CARBACHOL AND PILOCARPINE OF CILIARY MUSCLE IN VERVET AND CYNOMOLGUS MONKEYS
Author(s) -
BÄRÄNY ERNST H.
Publication year - 1977
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.1977.tb06103.x
Subject(s) - pilocarpine , ciliary muscle , carbachol , muscarinic acetylcholine receptor , anesthesia , chemistry , medicine , endocrinology , biology , accommodation , stimulation , epilepsy , receptor , neuroscience , psychiatry
Vervet monkeys were given unilateral treatment for two weeks with one 2% pilocarpine eye drop three times daily between 8 a. m. and 6 p. m. (night interval 14 h) and were then subjected to anterior chamber perfusion. 20 μg pilocarpine intracamerally caused similar and substantial increases in outflow facility in both eyes. Cynomolgus monkeys were unilaterally treated with continuous release of 33 μg/h of pilocarpine for 5–6 days. The facility response to 1 mg/kg pilocarpine iv was small or absent on the treated side. Iridectomized cynomolgus monkeys responded with 12.6±5.2 (SD) diopters accommodation to 1.5 mg/kg pilocarpine im, with very similar responses in the two eyes. During continuous release of 30 μg/h pilocarpine, accommodation of the treated eye dropped gradually and after 4–8 days treatment the accommodative response was markedly reduced to pilocarpine 1.5 mg/kg im or 100 μg topically. The degree of subsensitivity was much less when tested with either systemic or topical carbachol. This was also the case in a few vervet experiments. Recovery of full pilocarpine sensitivity took several weeks in the cynomolgus monkey. As an explanation for the excessive subsensitivity and large interindividual differences found with pilocarpine, an individually variable, non‐muscarinic relaxant action counteracting the muscarinic excitatory action is suggested. Clinical implications of this hypothesis are discussed.