Rate constants for recycling of muscarinic receptors after endocytosis in response to stimulation by various agonists
| Agonist | Recycling rate constant,kr | r2 |
|---|---|---|
| min−1 | ||
| Carbachol (1 mm) | 0.054 ± 0.004 | 0.997 |
| Methacholine (1 mm) | 0.053 ± 0.004 | 0.998 |
| Oxotremorine-M (1 mm) | 0.064 ± 0.008 | 0.999 |
| Bethanechol (10 mm) | 0.055 ± 0.002 | 0.999 |
| Arecoline (1 mm) | 0.061 ± 0.004 | 0.999 |
Cells were treated with agonist for 30 min at 37°C to induce receptor endocytosis. They were then washed free of agonist, and remaining surface receptors were alkylated with PrBCM at 15°C. PrBCM was washed away and the cells were warmed to 37°C to allow internal receptors to recycle, before measuring surface muscarinic receptor number using [3H]NMS, as in Fig. 2. Curves were fitted to eq. 3.