Steady-state catecholamine distribution in chromaffin granule preparations: a test of the pump-leak hypothesis of general anesthesia

Resealed chromaffin-granule ‘ghosts’ were used to study the steady-state kinetics of catecholamine transport. The pump has a high affinity for (-)-noradrenaline, (-)-adrenaline, tyramine and 5-hydroxytryptamine (serotonin), but a lower affinity for (+)-noradrenaline. The measured rates of incorporation do not conform to Michaelis–Menten kinetics, but affinity constants for the former substrates are in the range 8–18μm. Reserpine is a potent inhibitor. Incorporation as a function of ATP concentration also fails to show simple kinetics; the affinity constant for ATP is deduced to be about 3mm at 1mm-MgCl2. Adenylyl (βγ-methylene)diphosphonate is a competitive inhibitor at low concentrations, but inhibits more strongly at high concentrations. The pump has a transition temperature at 29°C and does not seem to be identical with the Mg2+-stimulated adenosine triphosphatase of chromaffin granules.

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Influence of Auditory Stimulation Rates on Evoked Potentials during General Anesthesia

Anesthesiology ◽

10.1097/aln.0b013e31819dad6f ◽

2009 ◽

Vol 110 (5) ◽

pp. 1026-1035 ◽

Cited By ~ 17

Author(s):

Richard R. McNeer ◽

Jorge Bohórquez ◽

Özcan Özdamar

Keyword(s):

Steady State ◽

General Anesthesia ◽

Stimulus Presentation ◽

Quantitative Relation ◽

Middle Latency Response ◽

Auditory Middle Latency Response ◽

Latency Response ◽

Middle Latency ◽

Composite Nature ◽

40 Hz

Background The auditory middle-latency response (transient) and the 40-Hz auditory steady state response (ASSR) are modulated by anesthetics. However, the quantitative relation between these evoked responses is difficult to obtain because of technical limitations of the recording methods used to obtain transients at high stimulation rates. This study uses continuous-loop averaging deconvolution to fill this technical gap and to study the relation between the transient and ASSR waveform during general anesthesia. Methods The authors recorded 5- and 40-Hz transients and 40-Hz ASSRs in 13 subjects during general anesthesia. The 5- and 40-Hz transients were used to predict the 40-Hz ASSR by linearly superimposing the transient waveforms. The predicted and recorded ASSRs were analyzed and compared using phasor and Hotelling T(2) analyses. Results Grand-averaged recordings revealed differences in the early middle-latency peaks between 5- and 40-Hz transients, e.g., the peak P(x) was present only in 5-Hz transient. Only the predicted 40-Hz ASSR derived from the 40-Hz transient matched the actual ASSR. Phasor analysis showed that the early peaks contribute significantly to the steady state waveform, and this explains why 5-Hz transient does not predict the 40-Hz ASSR. Oscillations in both the 5- and 40-Hz transients were observed during anesthesia. Discussion The 40-Hz ASSR represents a composite waveform and arises when transient waveforms elicited with a 40-Hz stimulation rate are overlapped and superimposed. During general anesthesia, the morphology of the transient is dependent on the rate of stimulus presentation. The composite nature of the ASSR may explain nonmonotonic anesthetic dose-response relations observed by others.

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Human Auditory Steady-State Response During General Anesthesia

Anesthesia & Analgesia ◽

10.1213/00000539-199011000-00002 ◽

1990 ◽

Vol 71 (5) ◽

pp. 460???468 ◽

Cited By ~ 86

Author(s):

G. Plourde ◽

T. W. Picton

Keyword(s):

Steady State ◽

General Anesthesia ◽

Steady State Response ◽

State Response ◽

Auditory Steady State Response

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Simultaneously extracted transient and steady-state evoked responses during general anesthesia: Variability of different rates

2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society ◽

10.1109/embc.2012.6346713 ◽

2012 ◽

Cited By ~ 1

Author(s):

A. Castro-Llanos ◽

J. Bohorquez ◽

R. R. McNeer ◽

O. Ozdamar

Keyword(s):

Steady State ◽

General Anesthesia ◽

Evoked Responses ◽

Transient And Steady State

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Studies on Water in the Hydration Chamber of a Modified Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069715 ◽

1970 ◽

Vol 28 ◽

pp. 544-545

Author(s):

R. C. Moretz ◽

G. G. Hausner ◽

D. F. Parsons

Keyword(s):

Thin Film ◽

Thin Films ◽

Electron Microscope ◽

Steady State ◽

Room Temperature ◽

Small Mass ◽

Equilibrium Pressure ◽

Biological Objects ◽

Mechanical Pump ◽

Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

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Continuous hydrogenolysis of acetal-stabilized lignin in flow

Green Chemistry ◽

10.1039/d0gc02928a ◽

2021 ◽

Author(s):

Wu Lan ◽

Yuan Peng Du ◽

Songlan Sun ◽

Jean Behaghel de Bueren ◽

Florent Héroguel ◽

...

Keyword(s):

Steady State ◽

Challenges And Opportunities

We performed a steady state high-yielding depolymerization of soluble acetal-stabilized lignin in flow, which offered a window into challenges and opportunities that will be faced when continuously processing this feedstock.

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