Effect of YM471, an orally active non-peptide arginine vasopressin receptor antagonist, on human vascular smooth muscle cells.
OBJECTIVE
To investigate the effects of YM471, a non-peptide arginine vasopressin (AVP) V1A and V2 receptor antagonist, on the AVP-induced growth responses in human vascular smooth muscle cells (VSMCs).


METHODS
Binding of YM471 to V1A receptors on VSMCs was measured using [3H]AVP. Intracellular free Ca2+ concentration was measured by fura 2 fluorescence. Mitogen-activated protein (MAP) kinase activity was determined using the p42/p44 MAP kinase specific peptide and [gamma- 32P]ATP as substrates. The effect of AVP on hyperplasia and hypertrophy of VSMCs was determined by cell number and protein content measurements.


RESULTS
YM471 potently and concentration-dependently inhibited the specific binding of [ 3H]AVP to V1A receptors on VSMCs, exhibiting an inhibition constant (Ki ) of 0.35 nmol/l. YM471 inhibited the AVP-induced increase in intracellular free Ca concentration with an 50% inhibition concentration (IC50 ) of 2.01 nmol/l and inhibited the activation of MAP kinase with an IC50 of 6.11 nmol/l. In addition, AVP concentration-dependently induced hyperplasia and hypertrophy in VSMCs, but YM471 prevented these AVP-induced growth effects, exhibiting IC50 values of 2.31 and 0.23 nmol/l, respectively.


CONCLUSIONS
These results indicate that YM471 has high affinity for V receptors on, and potently inhibits AVP-induced physiologic responses of, human VSMCs.
Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co. Ltd, Tsukuba, Ibaraki, Japan. tahara@yamanouchi.co.jp
Atsuo
A
Tahara
Junko
J
Tsukada
Yuichi
Y
Tomura
Toshiyuki
T
Kusayama
Koh-Ichi
K
Wada
Noe
N
Ishii
Takeyuki
T
Yatsu
Wataru
W
Uchida
Nobuaki
N
Taniguchi
Akihiro
A
Tanaka
D065092:Antidiuretic Hormone Receptor Antagonists; D001011:Aorta / Q000378:metabolism / Q000473:pathology; D001127:Arginine Vasopressin / Q000494:pharmacology; D001381:Azepines / Q000494:pharmacology*; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D006965:Hyperplasia; D006984:Hypertrophy; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000473:pathology; D010880:Piperidines / Q000494:pharmacology*; D017483:Receptors, Vasopressin / Q000378:metabolism
C432083:4'-(4,4-difluoro-5-(2-(4-dimethylaminopiperidino)-2-oxoethylidene)-2,3,4,5-tetrahydro-1H-1-benzoazepine-1-carbonyl)-2-phenylbenzanilide; D065092:Antidiuretic Hormone Receptor Antagonists; D001381:Azepines; D010880:Piperidines; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D020928:Mitogen-Activated Protein Kinases