Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2533025 | European Journal of Pharmacology | 2011 | 10 Pages |
We characterized agonist-induced internalization, recycling and downregulation of each muscarinic receptor subtype (M1–M5) stably expressed in Chinese hamster ovary (CHO) cells. The radioligands [3H]QNB and [3H]NMS were used to measure the total and plasma membrane populations of muscarinic receptors, respectively. Following carbachol treatment (1 mM), the rank orders for the rate of carbachol-induced internalization of the muscarinic subtypes were M2 > M4 = M5 > M3 = M1, respectively. Unlike the M2 receptor, M1, M3, M4 and M5 receptors recycled back to the plasma membrane after 1 h carbachol treatment. The receptor downregulation elicited to 24 h carbachol treatment was similar for M2, M3, M4 and M5 receptors, whereas that for the M1 receptor was greater. Our results indicate that there are subtype-specific differences in the rate and extent of agonist-induced muscarinic receptor internalization, recycling and downregulation in CHO cells.