The effects of veratramine on atrio-ventricular nodal rhythm and on auricular flutter in the dog heart-lung preparation

Benforado, Joseph M.; Dorner, Joe W.; Fuentes, Jaime

doi:10.1007/bf00244932

Cited by 2 publications

(1 citation statement)

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“…Likewise, the dose of propranolol used (1 mg/kg) completely blocked the response to 1 fig of isoproterenol given intracoronary. It is possible that veratridine has a direct negative chronotropic effect as a result of its action on SA and AV nodal tissue (Krayer et al, 1955;Benforado et al, 1961), although it is improbable that any of the injected veratridine could get to these areas from the left circumflex coronary artery, since we were injecting distal to the atrial branch of the left circumflex (James, 1977). However, it is not inconceivable that veratridine may have reached SA nodal tissue through some collateral branches.…”

Section: Discussionmentioning

confidence: 97%

The Bezold-Jarisch in the conscious dog.

Zucker¹,

Cornish²

1981

Circulation Research

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The Bezold-Jarisch reflex was studied in 22 conscious, instrumented dogs. Specific left ventricular receptor stimulation was elicited by the circumflex coronary artery injection of veratridine in doses ranging from 0.01 to 0.40 ftg/kg. None of these doses resulted in any hemodynamic effects when given intravenously. Heart rate, arterial blood pressure, left ventricular pressure, left ventricular dp/dt, and cardiac output were monitored and total peripheral resistance calculated. Dose-related decreases in arterial blood pressure and heart rate were observed following intracoronary injection of veratridine. Decreases were also noted in dp/dt max, left ventricular pressure, and cardiac output. With the heart paced to prevent bradycardia, the decrease in all the above parameters was significantly attenuated; however, a significant decrease in total peripheral resistance was still observed (-30.2 ± 3.7%). Cardiac pacing plus the administration of the a-adrenergic-blocking agent, phentolamine, blocked the decrease in total peripheral resistance when compared to pacing alone. The administration of atropine significantly attenuated the bradycardia, hypotension, decrease in dp/dt max, and decrease in total peripheral resistance in response to intracoronary veratridine. Atropine plus phentolamine abolished the decrease in total peripheral resistance that was evoked by intracoronary veratridine. The decrease in dp/dt max which resulted from veratridine administration was induced largely by the associated bradycardia, since both cardiac pacing and atropine significantly attenuated it. These experiments Indicate that the chemical stimulation of left ventricular receptors in the conscious dog mediates a bradycardia, hypotension and decrease in total peripheral resistance which is produced by sympathetic withdrawal as well as cholinergic vasodilation. There is no significant inotropic effect elicited by the stimulation of these receptors. Circ Res 49: [940][941][942][943][944][945][946][947][948] 1981

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Section: Discussionmentioning

confidence: 97%