Vascular smooth muscle cell NAD(P)H oxidase activity during the development of hypertension: Effect of angiotensin II and role of insulinlike growth factor-1 receptor transactivation.
OBJECTIVE
We investigated whether angiotensin II (Ang II)-induced reactive oxygen species (ROS) generation is altered in vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHR) during the phases of prehypertension, developing hypertension, and established hypertension and assessed the putative role of insulinlike growth factor-1 receptor (IGF-1R) in Ang II-mediated actions.


METHODS
The VSMCs from SHR and Wistar-Kyoto rats (WKY) aged 4 (prehypertensive), 9 (developing hypertension), and 16 (established hypertension) weeks were studied. The ROS production and NAD(P)H oxidase activation were determined by fluorescence and chemiluminescence, respectively. The role of IGF-1R was assessed with the selective inhibitor AG1024. The ROS bioavailability was manipulated with Tiron (10(-5) mol/L) and diphenylene iodonium (DPI) (10(-6) mol/L).


RESULTS
Angiotensin II dose dependently increased ROS production in WKY and SHR at all ages. The Ang II-induced responses were greater in SHR versus WKY at 9 and 16 weeks (P < .05). The Ang II-stimulated ROS increase was greater in 9- and 16-week-old SHR versus 4-week SHR (P < .05). These effects were reduced by AG 1024. Basal NAD(P)H oxidase activity was higher in VSMCs from 9-week-old SHR versus 4-week-old rats (P < .05). Angiotensin II induced a significant increase in oxidase activity in VSMCs from 9- and 16-week-old SHR (P < .001), without influencing responses in cells from 4-week-old SHR. Pretreatment of 9- and 16-week-old SHR cells with AG1024 reduced Ang II-mediated NAD(P)H oxidase activation (P < .05).


CONCLUSIONS
Basal and Ang II-induced NAD(P)H-driven ROS generation are enhanced in VSMCs from SHR during development of hypertension, but not in cells from prehypertensive rats. Transactivation of IGF-1R by Ang II may be important in vascular oxidative excess in the development of hypertension in SHR.
Cruzado
Montserrat C
MC
Department of Morphophysiology, School of Medicine, Universidad Nacional de Cuyo, Mendoza, Argentina. mcruzado@fcm.uncu.edu.ar
Risler
Norma R
NR
Miatello
Roberto M
RM
Yao
Guoying
G
Schiffrin
Ernesto L
EL
Touyz
Rhian M
RM
D000367:Age Factors; D000804:Angiotensin II / Q000502:physiology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D018929:Cell Culture Techniques; D004195:Disease Models, Animal; D006973:Hypertension / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D019255:NADPH Oxidases / Q000378:metabolism*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017382:Reactive Oxygen Species / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000502:physiology; D015533:Transcriptional Activation / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D017382:Reactive Oxygen Species; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D019255:NADPH Oxidases; D017526:Receptor, IGF Type 1; D020928:Mitogen-Activated Protein Kinases