Atrial receptor discharge in dogs with chronically induced difference in blood volume.

Abstract

SUMMARY1. Urinary responses to stimulation of atrial receptors have been found to be greater in dogs with a high blood volume than in dogs with a low blood volume. Two groups of dogs with different blood volume were examined by distending a large balloon in the left atrium, to stimulate atrial receptors and find out whether the increase in atrial receptor discharge was different in the two groups of dogs.2. The relationship between atrial receptor discharge and left atrial pressure was determined in twenty-six fibres studied in four dogs with a high blood volume and sixteen fibres studied in three dogs with a low blood volume.3. The slope of the relationship representing the increase in atrial receptor activity during increases in left atrial pressure, and the activity at each left atrial pressure, were significantly greater in dogs with a high blood volume than in dogs with a low blood volume.4. This study has shown that the atrial receptor discharge and their responses to increases in left atrial pressure are greater in dogs with a high blood volume than in those with a low blood volume.

Paradoxical Muscle Sympathetic Reflex Activation in Human Heart Failure

“…However, cardiac myelinated vagal afferents located primarily at venoatrial junctions elicit paradoxical reflex cardiac and peripheral sympathetic excitation when stimulated by similar mechanical stretch. 22 Discharge of such cardiac myelinated vagal afferents is augmented if intravascular 24 or atrial 25 volumes increase, as in HFrEF. Cardiac unmyelinated and myelinated sympathetic afferents found primarily within the left ventricle 26 also respond to both mechanical stretch and chemical stimuli by eliciting sympathoexcitation.…”

The relationship between left atrial pressure and atrial receptor discharge in dogs and cats with different body weights

“…The animals were prepared in the same way as previously reported by Hicks et al (1987). Briefly, pressure in the right femoral artery and the trachea were recorded together with the electrocardiogram.…”

“…The left cervical vagus was prepared for dissection to enable the recording of activity in vagal afferent fibres; the methods of preparation, the techniques for recording, monitoring and counting the activity, and the determination of conduction velocity were performed in the manner described by Hicks et al (1987) Hicks et al (1987).…”

“…More recently, Hicks, Mary & Walters (1987) used the same technique of distension of the large balloon in two groups of anaesthetized dogs with different blood volumes. They showed that the slope of the relationship between step increments in left atrial pressure and the resulting increases in the afferent discharge from atrial receptors with myelinated vagal afferent fibres was greater in dogs with a high blood volume than in those with a low blood volume.…”

“…The present study was performed using the same techniques as those employed by Hicks et al (1987) to determine whether the increase in atrial receptor discharge in response to incrementing left atrial pressure was different in dogs and cats of different body weight and atrial size. A preliminary report of this study has been presented to the International Union of Physiological Sciences (Hicks, Linden & Mary, 1986).…”