Spinal angiotensin II influences reflex cardiovascular responses to muscle contraction. 1995

C L Stebbins, and S Bonigut
Department of Internal Medicine, University of California, Davis 95616, USA.

We tested the hypothesis that inhibition of angiotensin II (ANG II) AT1 receptors in the thoracic spinal cord attenuates the reflex cardiovascular response to electrically induced hindlimb static contraction (exercise pressor reflex). Consequently, in alpha-chloralose-anesthetized cats, contraction-induced increases in mean arterial blood pressure, maximal rate of rise in left ventricular pressure (dP/dt), and heart rate were compared before and after intrathecal injection of the AT1 receptor antagonist losartan (100 or 1,000 micrograms; n = 7). Losartan significantly diminished increases in blood pressure and maximal dP/dt provoked by static contraction by 33 +/- 5 and 31 +/- 6%, respectively. Conversely, these contraction-induced responses were unaffected by similar injection of ANG II into the lumbosacral spinal cord (n = 5). Moreover, intravenous injection of 100 micrograms losartan did not affect the cardiovascular response to contraction. Our data suggest that ANG II has a excitatory effect on the efferent arm of the exercise pressor reflex, which may be due to a facilitatory action on sympathetic nerve activity.

UI MeSH Term Description Entries
D007093 Imidazoles Compounds containing 1,3-diazole, a five membered aromatic ring containing two nitrogen atoms separated by one of the carbons. Chemically reduced ones include IMIDAZOLINES and IMIDAZOLIDINES. Distinguish from 1,2-diazole (PYRAZOLES).
D007275 Injections, Intravenous Injections made into a vein for therapeutic or experimental purposes. Intravenous Injections,Injection, Intravenous,Intravenous Injection
D007278 Injections, Spinal Introduction of therapeutic agents into the spinal region using a needle and syringe. Injections, Intraspinal,Injections, Intrathecal,Intraspinal Injections,Intrathecal Injections,Spinal Injections,Injection, Intraspinal,Injection, Intrathecal,Injection, Spinal,Intraspinal Injection,Intrathecal Injection,Spinal Injection
D008161 Lumbosacral Region Region of the back including the LUMBAR VERTEBRAE, SACRUM, and nearby structures. Lumbar Region,Lumbar Regions,Lumbosacral Regions,Region, Lumbar,Region, Lumbosacral,Regions, Lumbar,Regions, Lumbosacral
D008297 Male Males
D009119 Muscle Contraction A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments. Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D012018 Reflex An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.
D002320 Cardiovascular Physiological Phenomena Processes and properties of the CARDIOVASCULAR SYSTEM as a whole or of any of its parts. Cardiovascular Physiologic Processes,Cardiovascular Physiological Processes,Cardiovascular Physiology,Cardiovascular Physiological Concepts,Cardiovascular Physiological Phenomenon,Cardiovascular Physiological Process,Physiology, Cardiovascular,Cardiovascular Physiological Concept,Cardiovascular Physiological Phenomenas,Concept, Cardiovascular Physiological,Concepts, Cardiovascular Physiological,Phenomena, Cardiovascular Physiological,Phenomenon, Cardiovascular Physiological,Physiologic Processes, Cardiovascular,Physiological Concept, Cardiovascular,Physiological Concepts, Cardiovascular,Physiological Phenomena, Cardiovascular,Physiological Phenomenon, Cardiovascular,Physiological Process, Cardiovascular,Physiological Processes, Cardiovascular,Process, Cardiovascular Physiological,Processes, Cardiovascular Physiologic,Processes, Cardiovascular Physiological
D002415 Cats The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801) Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D005260 Female Females

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