Involvement of ?2-Adrenoceptors in mechanism of intragastric nicotine protection against ethanol injury in rat stomach

Endoh, Kazuo; Kao, John; Baker, Margaret; Leung, Felix W.

doi:10.1007/bf01316805

Cited by 11 publications

(10 citation statements)

References 27 publications

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“…The number of mucosal lesions was counted [22]. The length of each lesion was measured by a caliper and summed to give the total length of mucosal lesions for each stomach [23].…”

Section: Methodsmentioning

confidence: 99%

Intragastric Nitroglycerin at a Vasodilatory Dose Attenuates Acidified Aspirin-Induced Gastric Mucosal Injury

Leung¹,

Chan

2007

Dig Dis Sci

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Clinical studies reveal that aspirin intake to prevent myocardial and cerebral ischemia is associated with a significant increase in upper gastrointestinal hemorrhage requiring hospitalization and that nitroglycerin or long-acting nitrates significantly lower this risk. Nitroglycerin can increase gastric blood flow and slow gastric emptying. We hypothesized that both features contribute to its gastroprotective property. Fasted anesthetized rats (Study 1) and conscious mice (Studies 2 to 4) received intragastric nitroglycerin or vehicle. The effects of these two treatments on various parameters were assessed in Study 1, on blood pressure and gastric blood flow; Study 2, on acidified aspirin-induced gastric mucosal lesions; and Study 3, on the weight of gastric content. In Study 4, the effect of nitroglycerin, vehicle, or vehicle plus saline, on acidified aspirin-induced gastric mucosal lesion was assessed. Compared with vehicle, nitroglycerin decreased blood pressure and produced a mild but significant increase in gastric vascular conductance, blood flow, and volume of gastric content. The number and length of gastric mucosal lesions induced by acidified aspirin were significantly attenuated by intragastric nitroglycerin in a vasodilatory dose. Exogenous saline in a volume equivalent to the increase produced by nitroglycerin, however, did not attenuate the lesions. These experimental data are consistent with the clinical observation that nitrates lower the risk of aspirin-induced gastrointestinal complications. Confirmation of the efficacy of nitroglycerin and nitrates in preventing such aspirin-induced complications in controlled trials is worthy of consideration by clinical investigators.

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“…The number of mucosal lesions was counted [22]. The length of each lesion was measured by a caliper and summed to give the total length of mucosal lesions for each stomach [23].…”

Section: Methodsmentioning

confidence: 99%

Intragastric Nitroglycerin at a Vasodilatory Dose Attenuates Acidified Aspirin-Induced Gastric Mucosal Injury

Leung¹,

Chan

2007

Dig Dis Sci

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“…The number of mucosal lesions was counted. The length of each lesion was measured by a caliper and summed to give the total length of mucosal lesions for each stomach [13,14].…”

Section: Methodsmentioning

confidence: 99%

“…A previous study reported that subcutaneous yohimbine (5 mg/kg) attenuated the protective effect of intragastric nicotine against ethanol-induced gastric mucosal injury [13]. Yohimbine pretreatment alone did not increase such injury [13].…”

Section: Study 3: Effect Of Yohimbine On the Protective Effect Of Nitmentioning

confidence: 98%

“…The α 2 -adrenoceoptors play a role in mediating the protective effect of intragastric nicotine [13]. Yohimbine did not alter the nicotine-induced increase in gastric juice volume or increase in titratable acid but significantly reduced the basal and nicotine-stimulated increase in gastric mucous volume [13]. Whether α 2 -adrenoceoptors contribute to the protective effect of intragastric nitroglycerin is not known.…”

Section: Introductionmentioning

confidence: 96%

“…The latter possibility has been assessed with regard to nicotine protection in gastric injury models in rats due to 40% ethanol [11] or acidified aspirin [12] but has not been considered with regard to NO protection against acidified ethanol-induced gastric injury. The α 2 -adrenoceoptors play a role in mediating the protective effect of intragastric nicotine [13]. Yohimbine did not alter the nicotine-induced increase in gastric juice volume or increase in titratable acid but significantly reduced the basal and nicotine-stimulated increase in gastric mucous volume [13].…”

Section: Introductionmentioning

confidence: 98%

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Involvement of α2-Adrenoceptors in the Gastric Protective Effect of Nitroglycerin Against Acidified Ethanol-Induced Mucosal Injury

Leung

Chan

2007

Dig Dis Sci

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Clinical observations reveal that alcohol intake is associated with an increase in upper gastrointestinal hemorrhage requiring hospitalization and that nitroglycerin or long-acting nitrates lower this risk. Nitroglycerin, a gastric vasodilator that can increase gastric fluid volume, protects the rodent stomach against damage, including that caused by 70% ethanol. Blockade of alpha(2)-adrenoceoptors attenuates gastric protection by intragastric nicotine against 40% ethanol. We tested the hypothesis that the protective effect of nitroglycerin is mediated by an increase in gastric fluid volume and alpha(2)-adrenoceoptors. Nitroglycerin, 5 mg/kg, vehicle, or acidified ethanol was administered intragastrically. In study 1 acidified ethanol-induced mucosal injury was measured. In study 2 the effect of increasing gastric volume (1 ml/kg) on mucosal injury was assessed. In study 3 the effect of yohimbine (alpha(2)-adrenoceoptor antagonist), 5 mg/kg subcutaneously, on the nitroglycerein-mediated protective effect was determined. Results showed that nitroglycerin significantly attenuated the number and length of mucosal lesions induced by acidified ethanol. Increase in gastric fluid volume by exogenously administered saline did not alter the protective effect. Yohimbine blocked the nitroglycerin-mediated protection. These experimental data are consistent with the observation that nitrates lower the risk of ethanol-induced gastrointestinal complications. alpha(2)-Adrenoceoptors are responsible in part for the protective effect of nitroglycerin.

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Intragastric nicotine protection against 40% ethanol injury in rat stomach

Endoh¹,

Kao²,

Baker³

et al. 1992

Digest Dis Sci

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Intragastric nicotine (4 mg/kg) protects against 40% ethanol-induced gastric mucosal injury and raises mean blood pressure. We postulated that this protective effect was mediated by the ganglionic stimulatory property of nicotine and therefore could be abolished by ganglionic blockers. Rats were pretreated with intraperitoneal hexamethonium (10 mg/kg) or mecamylamine (2 mg/kg) to block peripheral or central autonomic ganglia, respectively. Intragastric vehicle or nicotine (4 mg/kg) was then administered. The total lengths of the linear gastric corpus mucosal lesions induced by intragastric 40% ethanol were measured by an unbiased observer using a caliper. The results showed that both intraperitoneal hexamethonium and mecamylamine pretreatments protected against 40% ethanol-induced gastric mucosal injury. Neither modified the protective effect of intragastric nicotine. The protective effect of hexamethonium and mecamylamine was associated with a significant increase in the volume of gastric mucus and gastric juice. The increase in the volume of gastric content (mucus and juice) was partially responsible for the protective effect of these ganglionic blockers. In a separate experiment, intraperitoneal nicotine (4 mg/kg) also protected against 40% ethanol-induced gastric mucosal injury and raised mean blood pressure. These data indicate that the protection against 40% ethanol-induced gastric mucosal injury is not unique to intragastric nicotine. Such protection can be induced by ganglionic blocking doses of hexamethonium and mecamylamine, or a ganglionic stimulatory dose of intraperitoneally administered nicotine. Whether ganglionic stimulation or blockade plays a role in the mechanism of intragastric nicotine protection, however, remains to be determined.(ABSTRACT TRUNCATED AT 250 WORDS)

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Involvement of ?2-Adrenoceptors in mechanism of intragastric nicotine protection against ethanol injury in rat stomach

Cited by 11 publications

References 27 publications

Intragastric Nitroglycerin at a Vasodilatory Dose Attenuates Acidified Aspirin-Induced Gastric Mucosal Injury

Intragastric Nitroglycerin at a Vasodilatory Dose Attenuates Acidified Aspirin-Induced Gastric Mucosal Injury

Involvement of α2-Adrenoceptors in the Gastric Protective Effect of Nitroglycerin Against Acidified Ethanol-Induced Mucosal Injury

Intragastric nicotine protection against 40% ethanol injury in rat stomach

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