Autopotentiation of pressor responses by subpressor angiotensin II in rats. 1994

G Abraham, and G Simon
Department of Medicine, Veterans Affairs Medical Center, Minneapolis, MN 55417.

The mechanisms whereby the continuous administration of initially subpressor doses of angiotensin II (ANG II) leads to pressor hyperresponsiveness and gradual development of hypertension were investigated. Male Sprague-Dawley rats (350 to 400 g) were given ANG II intraperitoneally, 200 ng/kg/min, for 24 h, 7 to 10 days, or 6 weeks. Vehicle-infused rats were controls. Pressor responses to incremental doses of ANG II, norepinephrine (NE), and serotonin were measured in chloralose-anesthetized rats, before and after neurohumoral blockade, and the main findings were confirmed in awake, free-moving rats with implanted catheters. Pressure responses to ANG II and NE were also measured in the isolated, pump-perfused mesenteric circulation of rats after 7 to 10 days of ANG II or sham infusion. Compared with control rats, there were no hemodynamic changes in ANG II-treated rats at 24 h. After 7 to 10 days of ANG II treatment, tail systolic blood pressure rose by 13 mm Hg (P < .01) and pressor responses to ANG II (P < .01) but not to NE or serotonin were increased. Pressor hyperresponsiveness was due in part to potentiation of vascular responses because pressure responses to ANG II (P < .002) but not to NE were also increased in the mesenteric circulation of ANG II-treated rats. By 6 weeks, mild hypertension was well established in ANG II-treated rats and pressor responses were increased to both ANG II (P < .05) and NE (P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

UI MeSH Term Description Entries
D006973 Hypertension Persistently high systemic arterial BLOOD PRESSURE. Based on multiple readings (BLOOD PRESSURE DETERMINATION), hypertension is currently defined as when SYSTOLIC PRESSURE is consistently greater than 140 mm Hg or when DIASTOLIC PRESSURE is consistently 90 mm Hg or more. Blood Pressure, High,Blood Pressures, High,High Blood Pressure,High Blood Pressures
D007274 Injections, Intraperitoneal Forceful administration into the peritoneal cavity of liquid medication, nutrient, or other fluid through a hollow needle piercing the abdominal wall. Intraperitoneal Injections,Injection, Intraperitoneal,Intraperitoneal Injection
D008297 Male Males
D008969 Molecular Sequence Data Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories. Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D009638 Norepinephrine Precursor of epinephrine that is secreted by the ADRENAL MEDULLA and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers, and of the diffuse projection system in the brain that arises from the LOCUS CERULEUS. It is also found in plants and is used pharmacologically as a sympathomimetic. Levarterenol,Levonorepinephrine,Noradrenaline,Arterenol,Levonor,Levophed,Levophed Bitartrate,Noradrenaline Bitartrate,Noradrénaline tartrate renaudin,Norepinephrin d-Tartrate (1:1),Norepinephrine Bitartrate,Norepinephrine Hydrochloride,Norepinephrine Hydrochloride, (+)-Isomer,Norepinephrine Hydrochloride, (+,-)-Isomer,Norepinephrine d-Tartrate (1:1),Norepinephrine l-Tartrate (1:1),Norepinephrine l-Tartrate (1:1), (+,-)-Isomer,Norepinephrine l-Tartrate (1:1), Monohydrate,Norepinephrine l-Tartrate (1:1), Monohydrate, (+)-Isomer,Norepinephrine l-Tartrate (1:2),Norepinephrine l-Tartrate, (+)-Isomer,Norepinephrine, (+)-Isomer,Norepinephrine, (+,-)-Isomer
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
D001835 Body Weight The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms. Body Weights,Weight, Body,Weights, Body
D002698 Chloralose A derivative of CHLORAL HYDRATE that was used as a sedative but has been replaced by safer and more effective drugs. Its most common use is as a general anesthetic in animal experiments. Anhydroglucochloral,Glucochloral,Glucochloralose,alpha-Chloralose,beta-Chloralose,alpha Chloralose,beta Chloralose
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

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