Interaction of Baroreceptor and Chemoreceptor Reflexes MODULATION OF THE CHEMORECEPTOR REFLEX BY CHANGES IN BARORECEPTOR ACTIVITY

Abstract

A B S T R A C T The purpose of this study was to determine whether the level of arterial pressure and degree of baroreceptor activation affect responses to stimulation of chemoreceptors. Chemoreceptors were stimulated by injecting nicotine into the common carotid artery of anesthetized and paralyzed dogs. INTRODUCTIONHypotension and hypoxemia often occur together in the clinical setting, so the baroreceptors and chemoreceptors are affected simultaneously. In most studies of baroreceptor and chemoreceptor reflexes, however, the reflexes have been activated individually, and the possibility of interaction of reflexes has received little attention (2). Previous studies of the effect of systemic hypoxia on changes in heart rate in relation to changes in arterial pressure (3-5) do not permit definite conclusions concerning a possible interaction between baroreceptor and chemoreceptor reflexes.The purpose of this study was to examine the possibility that responses to stimulation of chemoreceptors might be affected by the level of arterial pressure. Chemoreceptors were activated by injection of nicotine into the common carotid artery (6) or by perfusing the carotid artery with hypoxic blood. The magnitude of reflex vasoconstrictor responses in the perfused gracilis muscle indicated the magnitude of the chemoreceptor reflex. Arterial pressure was lowered by bleeding the animals or raised transiently by inflating a balloon in the descending aorta.

Influence of fluvastatin on cardiac function and baroreflex sensitivity in diabetic rats

“…This result is not consistent with those of some DM models, which may be largely attributed to the different time course of development for diabetes (ie, 12, 24, and 48 weeks): metabolic disorders caused by a hyperglycemic state or insulinopenia may be related to time-dependent changes in parasympathetic and sympathetic control [25,26] and different osmotic diuresis after the DM model was established [27,28] . In addition, discrepancies in species, experimental design and diabetic inducer may also affect the results to some extent [29,30] . However, our results are consistent with the findings of Jackson and colleagues [31] that blood pressure responses to vasopressor agonists were depressed in STZ-induced DM rats while the baroreceptor reflexes in these rats were more sensitive to increases in blood pressure.…”

Enhanced Sympathetic and Ventilatory Responses to Central Chemoreflex Activation in Heart Failure

“…Increases in blood pressure and minute ventilation would each be expected to attenuate the sympathetic response to hypercapnia. 32,33 Very high baseline levels of sympathetic activity would also be expected to limit further increases in sympathetic drive. 34 Despite these considerations, hypercapnia elicited a Ͼ50% increase in the already-high levels of sympathetic nerve traffic in the CHF patients.…”

Carbon dioxide and venous return and their interaction as stimuli to ventilation in the cat

“…The effect of altering the volume of venous return upon respiration was probably first documented by Krogh & Linhard (1913) and subsequently confirmed by Bouckaert & Pannier (1942), Yeomans, Porter & Swank (1943), Mills (1944 and Brown, Goei, Greenfield & Plassavas (1966). Respiration has also been shown to be affected by intravenous infusion (Harrison, Harrison & Marsh, 1932;Coleridge & Linden, 1955;Hirsch, Boyd & Katz, 1964) while more recently, Wasserman et al (1974) have shown that an increase in cardiac output induced by electrical pacing or by isoproterenol is associated with hyperpnoea and that beta-adrenergic blockade causes hypopnoea (Brown, Wasserman & Whipp, 1976 (Lipski, McAllen & Trzebski, 1976), an action which will be enhanced by activation of arterial chemoreceptors which are sensitive to small, transient changes in perfusion pressure (Lee, Mayou & Torrance, 1964;Biscoe, Bradley & Purves, 1970) and possibly potentiated centrally (Heistad, Abboud, Mark & Schmid, 1974 Fig. 7).…”