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Updated: Aug 19, 2026

Subcutaneous Administration of Muscarinic Antagonists and Triple-Immunostaining of the Levator Auris Longus Muscle in Mice
Published on: September 8, 2011
Affinity of nortriptyline and its E-10-hydroxy metabolite for muscarinic receptors
1Kabi Pharma, Urology/Gynaecology, R & D, Stockholm, Sweden.
Abstract:
In the present investigation, the binding of nortriptyline and its active metabolite 10-hydroxynortriptyline (E-10-OH-NT) to muscarinic receptors was studied in the heart, parotid gland, cerebral cortex, urinary bladder and ileum from guinea pig. The affinity of E-10-OH-NT, as determined by competition with 1-quinuclidinyl (phenyl 4-3H)benzilate (-)3H-QNB), was about 10-12 times lower than that of nortriptyline in each tissue and none of the compounds seemed to exhibit any tissue selectivity. It is concluded that increased heart rate induced by E-10-OH-NT, but not by nortriptyline, cannot be attributed to a selective blockade of cardiac muscarinic receptors.
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