Clonidine, moxonidine, folic acid, and mecobalamin improve baroreflex function in stroke-prone, spontaneously hypertensive rats.
OBJECTIVE
To investigate the effect of clonidine, moxonidine, folic acid, and mecobalamin on arterial baroreflex (ABR) function in stroke-prone spontaneously hypertensive rats (SHR-SP) and the possible mechanisms involved.


METHODS
Eighty-one SHR-SP were divided into 7 groups. Four groups were designated for the intragastric (ig) administration of clonidine (1.0 and 10.0 microg/kg), moxonidine (0.1 and 1.0 mg/kg), folic acid (1.0 mg/kg), and mecobalamin (1.0 mg/kg). Three groups were for the intracerebroventricular (icv) injection of clonidine (4 microg/4 microL), moxonidine (5 microg/4 microL), and mecobalamin (20 microg/4 microL). Blood pressure (BP) was recorded in the conscious state for 30 min and baroreflex sensitivity (BRS) was determined respectively before and after drug administration.


RESULTS
Clonidine and moxonidine significantly decreased BP, prolonged the heart period (HP), and increased BRS when administered as either ig or icv injections. Both BP and HP were unchanged by ig folic acid or mecobalamin injection. However, BRS was significantly increased by both.


CONCLUSIONS
Clonidine, moxonidine, folic acid, and mecobalamin improved impaired ABR function in SHR-SP. The central mechanism was involved in this effect of either clonidine or moxonidine. Mecobalamin improved ABR function through the peripheral mechanism.
Ma
Xiu-Juan
XJ
Department of Pharmacology, Second Military Medical University, Shanghai 200433, China.
Shen
Fu-Ming
FM
Liu
Ai-Jun
AJ
Shi
Ke-Yong
KY
Wu
Ying-Liang
YL
Su
Ding-Feng
DF
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D017704:Baroreflex / Q000187:drug effects* / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D003000:Clonidine / Q000494:pharmacology*; D005260:Female; D005492:Folic Acid / Q000494:pharmacology; D006397:Hematinics / Q000494:pharmacology; D006973:Hypertension / Q000503:physiopathology*; D007093:Imidazoles / Q000494:pharmacology*; D011897:Random Allocation; D051381:Rats; D011918:Rats, Inbred SHR; D014805:Vitamin B 12 / Q000031:analogs & derivatives* / Q000494:pharmacology
D000959:Antihypertensive Agents; D006397:Hematinics; D007093:Imidazoles; D005492:Folic Acid; C019476:mecobalamin; C043482:moxonidine; D003000:Clonidine; D014805:Vitamin B 12