Like the M 1 and M 3 muscarinic receptor, M 5 receptors are coupled with G proteins of class Gq that upregulate phospholipase C and, therefore, inositol trisphosphate and intracellular calcium as a signaling pathway.
Radioactive iodine is a very effective type of treatment for cancer of the thyroid gland. Thyroid cells absorb iodine. The radioactive iodine from the drink or capsule is absorbed into your body and picked up by the thyroid cancer cells wherever they are. So it can kill the cancer cells even if they have spread.
This is a good question, and you're wise to be thinking ahead. As you know, radioactive iodine is taken to treat hyperthyroidism. You take one dose of the medication, and it's taken up by the thyroid gland where it destroys most of the thyroid tissue. Radioactive iodine does not spread to other body organs. It has not been linked to infertility, birth defects or cancer.