ABSTRACT
AIMS: We previously reported that mechanical atrial stretch (AS) by balloon distention increased gastric tonus in anesthetized rats. The present study evaluated the effect of AS on the gastric emptying of a liquid test meal in awake rats and its underlying neural mechanisms. MAIN METHODS: Anesthetized male rats received a balloon catheter into the right atrium and a gastrostomy cannula. The next day, mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), and cardiac output (CO) were continuously monitored. After the first 20min of monitoring (basal interval), the balloon was either distended or not (control) with 30, 50, or 70µl saline for 5min. Fifteen minutes later, the rats received the test meal (glucose solution with phenol red), and fractional gastric dye retention was determined 10, 20, or 30min later. KEY FINDINGS: Heart rate and CVP values were transiently increased by 50 or 70µl AS but not 30µl AS, whereas gastric emptying was slower after 30, 50, or 70µl AS than after sham distention. Subdiaphragmatic vagotomy or splanchnicotomy+celiac ganglionectomy and capsaicin, ondansetron, hexamethonium, L-NAME, and glibenclamide treatment prevented the AS-induced delay in gastric emptying, whereas atropine and guanethidine treatment failed to prevent it. SIGNIFICANCE: Atrial stretch inhibited the gastric emptying of liquid via non-adrenergic and non-cholinergic pathways that activate nitric oxide-K(+)ATP channels.
Subject(s)
Atrial Function, Right/physiology , Gastric Emptying/physiology , Gastrointestinal Transit/physiology , Heart Atria/surgery , Hypovolemia/physiopathology , Analysis of Variance , Animals , Atropine/pharmacology , Balloon Occlusion/methods , Blood Pressure , Capsaicin/pharmacology , Cardiac Catheterization/methods , Catheterization/methods , Gastric Emptying/drug effects , Gastrostomy/methods , Glyburide/pharmacology , Guanethidine/pharmacology , Heart Rate , Hexamethonium/pharmacology , Male , NG-Nitroarginine Methyl Ester/pharmacology , Nitric Oxide/blood , Ondansetron/pharmacology , RatsABSTRACT
Momordica charantia L. (Cucurbitaceae) é empregada na medicina popular pelas diversas propriedades biológicas e farmacológicas. Neste trabalho, objetivou-se avaliar a atividade hepatoprotetora dos extratos hexânico (EH) e etanólico (EE) das folhas de M. charantia no modelo de lesão hepática aguda induzida pelo etanol. Em ambos os extratos foram detectados esteróides; EH apresentou atividade antioxidante mais marcante que EE. O pré-tratamento de camundongos (Swiss, machos) por via oral por três dias consecutivos com 25, 50 ou 100 mg Kg-1 de EH preveniu o aumento tanto de AST quanto de ALT (p<0,05) enquanto o pré-tratamento com EE preveniu apenas o aumento de ALT (p<0,05). Ambos os extratos reduziram a atividade das enzimas hepáticas, contudo EH apresentou efeito mais relevante, caracterizando potencial hepatoprotetor, possivelmente associado ao seu potencial antioxidante.
Momordica charantia L. (Cucurbitaceae) has been used in folk medicine based on its several biological and pharmacological properties. The aim of this work was to evaluate the hepatoprotective activity of hexane (HE) and ethanol (EE) extracts from M. charantia leaves on the acute liver injury model induced by ethanol. Steroids were detected in both extracts, and EH had higher antioxidant activity than EE. Oral pretreatment of male Swiss mice for three consecutive days with 25, 50 or 100 mg kg-1 HE prevented the increase in AST and ALT (p<0.05), whereas pretreatment with EE only prevented ALT increase (p<0.05). Both extracts reduced the activity of hepatic enzymes; however, HE had a more relevant effect, characterizing hepatoprotective potential, likely associated with its antioxidant potential.
