Table 1.
Properties of the AR Subtypes in the Cardiovascular System.
| Subtype | Signal Transduction | Tissue Distribution | Physiological Function |
|---|---|---|---|
| α1A | Gq/G11/PLC/PKC/ DAG/IP3/Ca+2 |
Cardiac myocyte Vascular smooth muscle |
Positive inotropy, chronotropy, cardiac hypertrophy, contraction smooth muscle, blood pressure |
| α1B | Gq/G11/PLC/PKC/ DAG/IP3/Ca+2 |
Cardiac myocyte Vascular smooth muscle |
Negative inotropy, cardiac hypertrophy, contraction smooth muscle, blood pressure |
| α1D | Gq/G11/PLC/PKC/ DAG/IP3/Ca+2 |
Coronary arteries Vascular smooth muscle |
Contraction smooth muscle, blood pressure |
| α2A α2B α2C |
Gi/inhibit AC/ cAMP/PKA |
Not in any cardiac tissue Vascular smooth muscle |
NE release- Sympathetic nerve endings |
| β1 | Gs/AC/cAMP/PKA Ca+2 channel |
Cardiac myocyte | Positive inotropy, chronotropy, cardiac hypertrophy |
| β2 | Gs/AC/cAMP/PKA Ca+2 channel Gi/inhibit AC/ cAMP/PKA |
Cardiac myocyte Vascular smooth muscle |
Cardiac hypertrophy Relaxation smooth muscle |
| β3 | Gs/Gi/AC/cAMP/PKA NO |
Cardiac myocyte | Negative inotropy |
AC, adenylate cyclase; Ca+2, calcium; cAMP, cyclic adenosine monophosphate; DAG, diacylglycerol; IP3, inositol triphosphate; NE, norepinephrine; NO, nitric oxide; PKA, protein kinase A; PLC, phospholipase C.