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.
Iodine tablets can only protect the thyroid from radioactive iodine, and no other parts of the body. And, if the nuclear radiation does not contain radioactive iodine, then iodine tablets will have no effect. How much time elapses between exposure to radioactive iodine and the consumption of iodine tablets.