Rapid resetting of rabbit aortic baroreceptors and reflex heart rate responses by directional changes in blood pressure.

Burke, Sandra L.; Dorward, Patricia K.; Korner, Paul I.

doi:10.1113/jphysiol.1986.sp016226

Cited by 38 publications

(17 citation statements)

References 20 publications

(41 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One possibility is that IL-6 produces a change in heart rate control that can only be observed during the more sustained changes in blood pressure elicited by ET-1 and does not come into play during the more transient pressor responses to PE and ANG II. Rapid (minutes), although incomplete, resetting of baroreflexes has been described (4,22). Thus it may be possible that IL-6-infused mice display more rapid resetting of baroreflex control of heart rate than vehicleinfused mice.…”

Section: Discussionmentioning

confidence: 99%

Effect of chronic IL-6 infusion on acute pressor responses to vasoconstrictors in mice

Boesen¹,

Pollock²

2007

American Journal of Physiology-Heart and Circulatory Physiology

View full text Add to dashboard Cite

Interleukin (IL)-6 has been implicated as a contributing factor in the pathogenesis of hypertension, although the mechanisms involved are unclear. Studies conducted in vitro suggest that IL-6 may have a direct effect on vascular tone and may modulate constrictor responses to agonists. Whether this effect can be observed in vivo is unknown. Therefore, mice were treated with either IL-6 (16 ng/h sc) or vehicle for 14 days, and the acute blood pressure and heart rate responses to endothelin (ET)-1, angiotensin II (ANG II), and phenylephrine (PE) were assessed under isoflurane anesthesia. Blood pressure responses to ET-1 were identical in vehicle- and IL-6-infused mice, both in the presence and the absence of ganglion blockade with chlorisondamine. The fall in heart rate during ET-1 responses was significantly attenuated in IL-6-infused mice with autonomic reflexes intact (vehicle vs. IL-6, P < 0.05 at 1 and 3 nmol/kg of ET-1), but this difference was not observed after ganglionic blockade. Both blood pressure and heart rate responses to ANG II were indistinguishable between IL-6- and vehicle-infused mice, as were responses to PE except for a significant increase in the blood pressure response and decrease in the heart rate response in IL-6-infused mice observed only at the highest dose of PE (300 microg/kg; P < 0.05). These findings show that, despite what might be predicted from studies conducted in vitro, chronic exposure to elevated plasma IL-6 concentrations in itself does not predispose the mouse to enhanced responsiveness to vasoconstrictors in vivo.

show abstract

Section: Discussionmentioning

confidence: 99%

Effect of chronic IL-6 infusion on acute pressor responses to vasoconstrictors in mice

Boesen¹,

Pollock²

2007

American Journal of Physiology-Heart and Circulatory Physiology

View full text Add to dashboard Cite

show abstract

“…More recently, it was demonstrated that the rapid (acute) resetting occurs within the first few minutes after an increase or decrease in blood pressure (20,21). Moreover, in rabbits, arterial baroreceptor resetting is known to be very rapid, starting about 30 s after any sustained change in resting mean arterial pressure is produced (22). Thus, to prevent a strong interference of the resetting mechanisms, blood pressure must be changed quickly.…”

Section: Discussionmentioning

confidence: 99%

Comparison of three methods for the determination of baroreflex sensitivity in conscious rats

Farah

Moreira

Pires

et al. 1999

Braz J Med Biol Res

View full text Add to dashboard Cite

Baroreflex sensitivity was studied in the same group of conscious rats using vasoactive drugs (phenylephrine and sodium nitroprusside) administered by three different approaches: 1) bolus injection, 2) steady-state (blood pressure (BP) changes produced in steps), 3) ramp infusion (30 s, brief infusion). The heart rate (HR) responses were evaluated by the mean index (mean ratio of all HR changes and mean arterial pressure (MAP) changes), by linear regression and by the logistic method (maximum gain of the sigmoid curve by a logistic function). The experiments were performed on three consecutive days. Basal MAP and resting HR were similar on all days of the study. Bradycardic responses evaluated by the mean index (-1.5 ± 0.2, -2.1 ± 0.2 and -1.6 ± 0.2 bpm/mmHg) and linear regression (-1.8 ± 0.3, -1.4 ± 0.3 and -1.7 ± 0.2 bpm/mmHg) were similar for all three approaches used to change blood pressure. The tachycardic responses to decreases of MAP were similar when evaluated by linear regression (-3.9 ± 0.8, -2.1 ± 0.7 and -3.8 ± 0.4 bpm/mmHg). However, the tachycardic mean index (-3.1 ± 0.4, -6.6 ± 1 and -3.6 ± 0.5 bpm/mmHg) was higher when assessed by the steady-state method. The average gain evaluated by logistic function (-3.5 ± 0.6, -7.6 ± 1.3 and -3.8 ± 0.4 bpm/mmHg) was similar to the reflex tachycardic values, but different from the bradycardic values. Since different ways to change BP may alter the afferent baroreceptor function, the MAP changes obtained during short periods of time (up to 30 s: bolus and ramp infusion) are more appropriate to prevent the acute resetting. Assessment of the baroreflex sensitivity by mean index and linear regression permits a separate analysis of gain for reflex bradycardia and reflex tachycardia. Although two values of baroreflex sensitivity cannot be evaluated by a single symmetric logistic function, this method has the advantage of better comparing the baroreflex sensitivity of animals with different basal blood pressures. mate the sensitivity of the baroreceptor reflex using a single value represented by the maximum gain of the baroreflex curve at the midpoint of the sigmoid curve (15-17). In addition, this method permits the calculation of the upper and lower HR plateau, the HR range, average gain (slope between the two inflection points) and a blood pressure parameter halfway between the lower and upper plateau (BP50).Each of these procedures employed to produce alterations in blood pressure and to analyze the heart rate responses has been used to study the baroreflex control of heart rate during physiological states (exercise, postural changes and sleep) or during pathological conditions (hypertension, hemorrhage and myocardial infarction). However, the different methods have not been compared in the same individual. Thus, the purpose of the present study was to compare in the same conscious rat the three methods used to alter blood pressure, i.e., bolus injection, steadystate and ramp infusion, and to compare the values of baroreflex sensitivity analyzed by the ...

show abstract

“…Munch et al (37), using an in vitro preparation of the rat aortic arch, showed that when a step rise in arterial pressure was maintained, single-fiber baroreceptor activity declined exponentially with a time constant of 3-4 min. Reports of resetting over an even shorter time frame have been reported (6). Resetting of the arterial baroreceptors is also observed in chronic hypertension, although it should be noted that the shift in the arterial pressure-baroreceptor activity relationship is rarely found to be complete (see Ref.…”

Section: First Argument Against Arterial Baroreflexes Playing a Role mentioning

confidence: 99%

Problems, possibilities, and pitfalls in studying the arterial baroreflexes’ influence over long-term control of blood pressure

Barrett

Malpas

2005

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

While there is no disputing the critical role of baroreflexes in buffering rapid changes in arterial pressure, their role in long-term pressure control has become an area of controversy. Recent experiments using novel techniques have challenged the traditional view that arterial baroreflexes are not involved in setting chronic arterial pressure levels. Resetting of the arterial baroreflex, often used as an argument against the arterial baroreflex playing a role in long-term pressure control is rarely complete. The arterial baroreflex is just one of the many neural, hormonal, and intrinsic mechanisms involved in arterial pressure control and while the removal of the arterial baroreflex alone has little effect on mean arterial pressure it is too simplistic to suggest that the baroreflex has no role in long-term pressure control. Renal sympathetic nerve activity appears to be particularly resistant to resetting in response to ANG II-induced hypertension. Given the important role of the kidneys in long-term pressure control, we suggest there is a clear need to develop experimental techniques whereby sympathetic nerve activity to the kidneys and other organs can be monitored over periods of weeks to months.

show abstract

Rapid resetting of rabbit aortic baroreceptors and reflex heart rate responses by directional changes in blood pressure.

Cited by 38 publications

References 20 publications

Effect of chronic IL-6 infusion on acute pressor responses to vasoconstrictors in mice

Effect of chronic IL-6 infusion on acute pressor responses to vasoconstrictors in mice

Comparison of three methods for the determination of baroreflex sensitivity in conscious rats

Problems, possibilities, and pitfalls in studying the arterial baroreflexes’ influence over long-term control of blood pressure

Contact Info

Product

Resources

About