Small signal characteristics of carotid sinus baroreceptors of rabbits.

Franz, G.; Scher, Allen M.; Ito, C S

doi:10.1152/jappl.1971.30.4.527

Cited by 45 publications

(32 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar restrictions also were present in other studies (Srinivasan and Nudelman, 1972;Christensen, 1967;Clarke, 1968;Franz, 1969). An alternative approach is to use pressure sine waves, and some studies of this sort have been done (Angell-James, 1971;Arndt et al, 1975;Franz et al, 1971). However, these studies gave insufficient information on receptor responses at higher frequencies and did not consider differences between UB's and MB's.…”

Section: Dynamic Responses Of Baroreceptorsmentioning

confidence: 74%

“…The frequency response can be modeled by a cascade of transfer functions, the first of which gives a complex second-order response and has a differential equation similar to that used in Equation 11 of Franz et al (1971). However, calculations with this transfer function alone cannot produce the peaking shown by MB's at 4-6 Hz, since they give an amplitude ratio of about 1.1 for frequencies greater than 0.06 Hz.…”

Section: Dynamic Responses Of Baroreceptorsmentioning

confidence: 99%

See 1 more Smart Citation

Receptors under pressure. An update on baroreceptors.

Brown¹

1980

Circulation Research

211

View full text Add to dashboard Cite

Section: Dynamic Responses Of Baroreceptorsmentioning

confidence: 74%

Section: Dynamic Responses Of Baroreceptorsmentioning

confidence: 99%

Receptors under pressure. An update on baroreceptors.

Brown¹

1980

Circulation Research

211

View full text Add to dashboard Cite

“…In isolated vascular segments, on the other hand, relatively simple waveforms of varying amplitude and duration usually have been applied round a constant mean pressure. In experiments of the latter type (Franz, 1969;Franz et al, 1971), the overshoot and undershoot of the carotid baroreceptor response to suprathreshold square waves of pressure were both included in the general term "bidirectional rate sensitivity," and as such were held to be manifestations of the viscoelastic properties of the arterial wall. The mechanisms responsible for the phenomena of baroreceptor overshoot and undershoot in the rat aortic arch preparation have been examined in detail by Saum et al (1976).…”

Section: Discussionmentioning

confidence: 99%

Operational sensitivity and acute resetting of aortic baroreceptors in dogs.

Coleridge¹,

Coleridge²,

Kaufman

et al. 1981

Circulation Research

View full text Add to dashboard Cite

SUMMARY Stimulus-response curves of aortic baroreceptors constructed by alternately increasing and decreasing pressure from a normal baseline or set-point differ from curves constructed by varying pressure in one direction only from an abnormally high or low pressure. In anesthetized dogs we recorded impulses from aortic baroreceptors with myelinated fibers, using a pressurized reservoir to control mean aortic blood pressure (MABP). After setting MABP to a baseline of 100 mm Hg (normal MABP in unanesthetized dogs), we constructed baroreceptor response curves by alternately decreasing MABP from 100 to 30 mm Hg, and increasing it from 100 to 180 mm Hg, in each case returning MABP to the baseline to obtain hysteresis loops. All baroreceptors were active at 100 mm Hg, their discharge averaging 15-16 impulses/sec. At all pressures above threshold, baroreceptors fired more when pressure was increasing than when pressure was decreasing. This hysteresis caused the steepest part of the response curve constructed in this manner to span the baseline value, demonstrating that, contrary to previous views, aortic baroreceptors signal decreases in pressure below the normal level, as well as increases above it. We also constructed response curves after holding MABP at a "hypertensive" baseline of 125 mm Hg for 20 minutes. "Hypertensive" curves demonstrated reversible resetting, shifting significantly to the right of "normotensive" curves so that baroreceptor threshold increased on average by 7 mm Hg ( P < 0.01). Both hysteresis and short-term resetting probably result from the viscoelastic behavior of wall elements with which baroreceptors are coupled. Circ Res 48: 676-684, 1981 THE ROLE of aortic baroreceptors in regulating blood pressure is controversial. From the results of an electroneurographic study in dogs, Pelletier et al. (1972) concluded that at normal arterial pressure the aortic nerve displays little baroreceptor activity and that, rather than acting as a true buffer system, aortic baroreceptors have a predominantly antihypertensive role. However, two recent studies in conscious dogs indicate that when the carotid sinus nerves are cut the aortic nerves alone can buffer decreases, as well as increases, in arterial pressure (McRitchie et al., 1976;Ito and Scher, 1978). This apparent conflict of evidence about a fundamental aspect of the functions of aortic baroreceptors in dogs suggests that a reexamination of their afferent properties is timely.In studies of the stimulus-response characteristics of arterial baroreceptors, the common practice is either to increase pressure until firing frequency is maximal and then to examine baroreceptor response as pressure is reduced (Fig. 1A), or to reduce pressure below baroreceptor threshold and then to examine the response as pressure is increased (Fig.

show abstract

“…8 The transient response to step stimuli has an initial rise which is rapid but not instantaneous; this was either overlooked or ignored previously. 6 The transient develops an overshoot followed by a slow relaxation to a steady state discharge. These qualitative features are similar in MBs and UBs.…”

Section: Discussionmentioning

confidence: 99%

Baroreceptor dynamics and their relationship to afferent fiber type and hypertension.

Brown¹,

Saum²,

Yasui³

1978

Circulation Research

View full text Add to dashboard Cite

SUMMARY Static characteristics of baroreceptors differ depending on whether receptors are connected to myelinated or unmyelinated axons (MBs and UBs) and whether they come from normotensive or spontaneously hypertensive rats (NTRs and SHRs). Dynamic characteristics are incompletely known and were examined using an in vitro rat aortic arch-aortic nerve preparation in which static characteristics are similar to those present in vivo. Small amplitude sinusoidal pressures were applied at frequencies varying from 0.1 to 20 Hz over the range of linear responses to pressure. MBs from SHRs and NTRs show peaking in curves relating gain to frequency, gain being the ratio of sinusoidal discharge-rate amplitude and sine wave pressure amplitude. Similar curves from UBs of NTRs and SHRs are overdamped and show no such peaking. In MBs, the response phase leads initially, starts to lag around resonant frequencies, and falls behind progressively thereafter. In UBs, the phase also leads initially, then lags monotonically to about -60°. The discharge rectifies at high frequencies probably as the result of nonlinear threshold properties of the spike-initiating zone. The dynamic response curves of SHR and NTR aortas also were determined and found to be flat to much higher frequencies than those of the baroreceptors. Thus aortic wall dynamics do not limit the frequency range of the baroreceptors. There are no differences between NTRs and SHRs in the dynamics of either their aortas or their baroreceptors. The differences in dynamics between MBs and UBs may be due to differences in mechanical coupling related to structural differences between their endings.CARDIOVASCULAR baroreceptors are connected to the central nervous system by either myelinated or unmyelinated axons.1 The reflexes elicited by electrical stimulation of the two groups, which will be referred to as MBs and UBs, differ quantitatively and qualitatively. Electrical excitation of unmyelinated afferents in the aortic nerve produces more profound depressor reflexes than excitation of myelinated afferents (Fig. 1 in paper ). Moreover, electrical excitation of myelinated cardiac vagal afferents may produce tachycardia, whereas excitation of both myelinated and unmyelinated cardiac vagal afferents elicits marked depressor effects. 3These results emphasize the differences in the central connections of MBs and UBs but do not address the question of the functional differences between the two groups of receptors. Recently, Thoren and Thoren et al. have compared the static characteristics of aortic MBs and UBs and found that the threshold is higher and the sensitivity to suprathreshold pressures is lower in UBs. The dynamic characteristics have not been compared, however. A comparison would clearly be important since cardiovascular pressures are normally phasic and the discharge of MBs and UBs has frequency-dependent components.-In addition, the dynamic characteristics of baroreceptors are largely unknown except for a few receptors which have been studied over limited frequency and

show abstract

Small signal characteristics of carotid sinus baroreceptors of rabbits.

Cited by 45 publications

References 0 publications

Receptors under pressure. An update on baroreceptors.

Receptors under pressure. An update on baroreceptors.

Operational sensitivity and acute resetting of aortic baroreceptors in dogs.

Baroreceptor dynamics and their relationship to afferent fiber type and hypertension.

Contact Info

Product

Resources

About