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.
Truth is, iodine is a very good antiseptic (kills germs dead on contact). It is also a very good antibiotic. Its use as an antibiotic/antiviral/anti-fungal has been completely ignored by modern medicine. But iodine works against microbes in two ways: 1. It kills germs, as I said, though when taken internally, you have to adjust the dose, of course, to avoid hurting the patient.