Biomaterial Database

Subfornical organ lesion attenuates chronic hypotensive effects of losartan in salt-replete rats. 2003

John P Collister, and Michael D Hendel

Department of Veterinary Pathobiology, University of Minnesota, St Paul, Minnesota 55108, USA. colli066@tc.umn.edu

HYPOTHESIS/INTRODUCTION: Circumventricular organs are central nervous system brain sites thought to participate in neuroendocrine regulation of neural output. We have previously demonstrated a profound chronic hypotensive response to the angiotensin II (Ang II) AT(1) antagonist, losartan (10 mg/kg/day), in normal rats. In addition, we have demonstrated that the area postrema, one of the circumventricular organs, partially mediates this response. The subfornical organ (SFO) is another circumventricular organ which has been shown to mediate actions of Ang II. The present study was designed to test the hypothesis that the SFO mediates the chronic hypotensive effects of losartan in normal rats. METHODS Rats were randomly chosen for lesion of the SFO or sham operation and instrumented with intravenous catheters and radiotelemetric blood pressure transducers. After a control period, rats were infused with losartan (10 mg/kg/day) for nine days. Mean arterial pressure and heart rate responses were measured continuously throughout the protocol and examined as 12-hour day/night averages. RESULTS By day 7 of losartan treatment, night-time mean arterial pressure had dropped to 75+2 mmHg in sham rats (n=8) but only to 83+2 mmHg in SFO-lesioned rats (n=10). This trend continued throughout the treatment protocol. CONCLUSIONS These results suggest that the SFO partially mediates the chronic hypotensive effects of chronic losartan treatment in normal rats.

UI	MeSH Term	Description	Entries
D007022	Hypotension	Abnormally low BLOOD PRESSURE that can result in inadequate blood flow to the brain and other vital organs. Common symptom is DIZZINESS but greater negative impacts on the body occur when there is prolonged depravation of oxygen and nutrients.	Blood Pressure, Low,Hypotension, Vascular,Low Blood Pressure,Vascular Hypotension
D008297	Male		Males
D012083	Renin	A highly specific (Leu-Leu) endopeptidase that generates ANGIOTENSIN I from its precursor ANGIOTENSINOGEN, leading to a cascade of reactions which elevate BLOOD PRESSURE and increase sodium retention by the kidney in the RENIN-ANGIOTENSIN SYSTEM. The enzyme was formerly listed as EC 3.4.99.19.	Angiotensin-Forming Enzyme,Angiotensinogenase,Big Renin,Cryorenin,Inactive Renin,Pre-Prorenin,Preprorenin,Prorenin,Angiotensin Forming Enzyme,Pre Prorenin,Renin, Big,Renin, Inactive
D001794	Blood Pressure	PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.	Systolic Pressure,Diastolic Pressure,Pulse Pressure,Pressure, Blood,Pressure, Diastolic,Pressure, Pulse,Pressure, Systolic,Pressures, Systolic
D001834	Body Water	Fluids composed mainly of water found within the body.	Water, Body
D002908	Chronic Disease	Diseases which have one or more of the following characteristics: they are permanent, leave residual disability, are caused by nonreversible pathological alteration, require special training of the patient for rehabilitation, or may be expected to require a long period of supervision, observation, or care (Dictionary of Health Services Management, 2d ed). For epidemiological studies chronic disease often includes HEART DISEASES; STROKE; CANCER; and diabetes (DIABETES MELLITUS, TYPE 2).	Chronic Condition,Chronic Illness,Chronically Ill,Chronic Conditions,Chronic Diseases,Chronic Illnesses,Condition, Chronic,Disease, Chronic,Illness, Chronic
D006339	Heart Rate	The number of times the HEART VENTRICLES contract per unit of time, usually per minute.	Cardiac Rate,Chronotropism, Cardiac,Heart Rate Control,Heartbeat,Pulse Rate,Cardiac Chronotropy,Cardiac Chronotropism,Cardiac Rates,Chronotropy, Cardiac,Control, Heart Rate,Heart Rates,Heartbeats,Pulse Rates,Rate Control, Heart,Rate, Cardiac,Rate, Heart,Rate, Pulse
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000959	Antihypertensive Agents	Drugs used in the treatment of acute or chronic vascular HYPERTENSION regardless of pharmacological mechanism. Among the antihypertensive agents are DIURETICS; (especially DIURETICS, THIAZIDE); ADRENERGIC BETA-ANTAGONISTS; ADRENERGIC ALPHA-ANTAGONISTS; ANGIOTENSIN-CONVERTING ENZYME INHIBITORS; CALCIUM CHANNEL BLOCKERS; GANGLIONIC BLOCKERS; and VASODILATOR AGENTS.	Anti-Hypertensive,Anti-Hypertensive Agent,Anti-Hypertensive Drug,Antihypertensive,Antihypertensive Agent,Antihypertensive Drug,Anti-Hypertensive Agents,Anti-Hypertensive Drugs,Anti-Hypertensives,Antihypertensive Drugs,Antihypertensives,Agent, Anti-Hypertensive,Agent, Antihypertensive,Agents, Anti-Hypertensive,Agents, Antihypertensive,Anti Hypertensive,Anti Hypertensive Agent,Anti Hypertensive Agents,Anti Hypertensive Drug,Anti Hypertensive Drugs,Anti Hypertensives,Drug, Anti-Hypertensive,Drug, Antihypertensive,Drugs, Anti-Hypertensive,Drugs, Antihypertensive
D012964	Sodium	A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.	Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23