Metabotropic receptor

A metabotropic receptor, also referred to by the broader term G-protein-coupled receptor, is a type of membrane receptor that initiates a number of metabolic steps to modulate cell activity. The nervous system utilizes two types of receptors: metabotropic and ionotropic receptors. While ionotropic receptors form an ion channel pore, metabotropic receptors are indirectly linked with ion channels through signal transduction mechanisms, such as G proteins. These two types of receptors, along with their number and activity level, form the basis of the sympathetic and parasympathetic nervous systems and play key roles in regulating rates of resting energy expenditure (REE), resting heart rate, heart rate variability, and global myocardial oxygen consumption.

Both receptor types are activated by specific chemical ligands. When an ionotropic receptor is activated, it opens a channel that allows ions such as Na⁺, K⁺, or Cl⁻ to flow. In contrast, when a metabotropic receptor is activated, a series of intracellular events are triggered that can also result in ion channels opening or other intracellular events, but involve a range of second messenger chemicals.