Clonidine abolishes exaggerated pressor responses to shaker stress in spontaneously hypertensive rats.
To determine whether clonidine would attenuate exaggerated pressor responses to stress in spontaneously hypertensive rats (SHR), pressor responses to shaker stress were recorded following intracerebroventricular (icv) injections of clonidine in conscious SHR. Pressor responses to shaker stress were significantly larger in SHR than in Wistar-Kyoto rats (WKY). Increased sympathetic nerve responses to shaker stress were also significantly greater in SHR than in WKY. Exaggerated pressor responses in SHR were partly attenuated by adrenalectomy and abolished by clonidine (icv). By contrast, 1-Sar,8-Ile angiotensin II (icv) was ineffective. These findings suggest that in SHR, the alpha-adrenergic system in the brain may contribute to exaggerated pressor responses to shaker stress, but not the brain renin-angiotensin system.
Takeda
K
K
Second Department of Internal Medicine, Kyoto Prefectural University of Medicine, Japan.
Okajima
H
H
Nakata
T
T
Kawasaki
S
S
Hayashi
J
J
Oguro
M
M
Sasaki
S
S
Nakagawa
M
M
D015059:1-Sarcosine-8-Isoleucine Angiotensin II / Q000008:administration & dosage / Q000494:pharmacology; D000315:Adrenalectomy; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002490:Central Nervous System / Q000187:drug effects / Q000503:physiopathology; D003000:Clonidine / Q000494:pharmacology*; D006973:Hypertension / Q000188:drug therapy / Q000503:physiopathology; D007276:Injections, Intraventricular; D011311:Pressoreceptors / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects* / Q000502:physiology; D012084:Renin-Angiotensin System / Q000187:drug effects / Q000502:physiology; D013312:Stress, Physiological / Q000188:drug therapy / Q000503:physiopathology
D011942:Receptors, Adrenergic, alpha; D015059:1-Sarcosine-8-Isoleucine Angiotensin II; D003000:Clonidine