Smooth Myocytes - Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems - page 434

Table 8.20. Direct vasoconstrictors that activate GPCRs. ( Part 2 ) Gq/11-coupled receptors.
Activation of members of the group of G ,

hence provoking activation of myosin light chain kinase via inositol (1,4,5)-trisphosphate, Ca 2 +
influx, and Ca 2 + -calmodulin, as well as inhibition of myosin light chain phosphatase via
diacylglycerol, protein kinase-C, protein phosphatase-1, a phosphorylation-dependent inhibitor
protein of smooth muscle m yosin phosphatase.

α q/11-protein subunits stimulates phospholipase-C β

GPCR Type Agonist

M 1 ,M 2 Acetylcholine

α 1a/1b/1c Adrenaline, noradrenaline

P2Y 1 ADP

P2Y 2 AT P, U T P

P2Y 6 UDP

5HT 2A Serotonin

H 1 Histamine

AT 1 Angiotensin-2

ET A / B Endothelin-1

NK 2 Neurokinin-A

NMU 1 Neuromedin-U

UT Urotensin-2

V 1A Vasopressin

EP 1 Prostaglandin-E2

TP Thromboxane-A2

CysLT 1 Leukotriene-D4

S1P 2 / 3 Sphingosine 1-phosphate

PA R 1 Thrombin

Table 8.21. Direct vasoconstrictors that activate GPCRs. ( Part 3 ) G12/13-coupled receptors.
Activation of members of the group of G 12/13-protein subunits activates small GTPase Rho,

hence Rho kinase that inhibi ts myosin light chain phosphatase.

α

GPCR Type Agonist

AT 1 Angiotensin-2

ET A Endothelin-1

TP Thromboxane-A2

S1P 2 / 3 Sphingosine 1-phosphate

PA R 1 Thrombin

of molecular oxygen into arachidonic acid happens in a 2-step reaction. The first
reaction yields 5-hydroperoxyeicosatetraenoic acid (5HPETE). Product 5HPETE
can form 2 types of 5LOx metabolites: either unstable LTa4 (half-life 3s at

physiological pH) or stable 5-hydroxyeicosatetraenoic acid (5HETE) that has a
slight biological activity. Derivative 5HETE is the precursor of potent 5-oxo-ETE
eicosanoid involved in eosinophil chemotaxis. On the other hand, soluble LTa4
hydrolase produces LTb4, a powerful pro-inflammatory agent. LTb4 Mediator is
secreted through the LTb4 transporter or can act in the nucleus as a transcription
modulator. Messenger LTb4 targets BLT 1 and BLT 2 receptors. (2) At the plasma

<