| 41121. |
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| 41122. |
- Wennergren, Göran, 1947, et al.
(författare)
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Cardiac receptors activated during the hypothalamic defence reaction.
- 1977
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 101:2, s. 241-6
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Tidskriftsartikel (refereegranskat)abstract
- The increases of arterial blood pressure, cardiac inotropy and venous return seen during the hypothalamic defence reaction are likely to lead to concomitant excitation of left ventricular receptors with nonmedullated afferents. The integrated efferent pattern of response resulting from the central interaction between the defence reaction and influences from the mentioned cardiac receptors was recently analyzed. These two, essentially opposing influences on the circulation were then seen to interact in such a way as to produce an optimal cardiovascular response with respect to increases in cardiac output and blood supply to the skeletal muscles. However, direct electrophysiological recordings from nonmedullated cardiac efferents during defence area stimulation have hitherto been lacking. The present experiments, performed on chloralose-anesthetized cats and utilizing electrophysiological recordings, clearly demonstrate that the left ventricular receptors are activated by the cardiovascular readjustments induced by the defence reaction. Defence area stimulation increased the activity of these receptors, which work within a very narrow, low frequency range, from 1.1 +/- 0.3 imp/s to 2.7 +/- 0.7 imp/s associated with rises in systolic blood pressure (afterload) and heart rate. Normally such a receptor activation would induce considerable bradycardia and sympathetic inhibition, but particularly the reflex bradycardia is centrally supressed by a concomitant defence area activation. The marked bradycardia often seen immediately upon interruption of the defence area stimulation is, however, probably to a great extent initiated from the excited ventricular receptors.
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| 41123. |
- Wennergren, Göran, 1947, et al.
(författare)
-
Cardiovascular effects elicited from the ventral surface of medulla oblongata in the cat.
- 1980
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Ingår i: Pflugers Archiv : European journal of physiology. - 0031-6768. ; 387:2, s. 189-95
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Tidskriftsartikel (refereegranskat)abstract
- Cardiovascular adjustments induced by topical application of drugs on a restricted area on the ventral surface of the medulla oblongata, corresponding to the caudal part of the rostral chemoreceptor area and the intermediate area, have been studied in chloralose-anesthetized cats. Topical application of GABA or glycine on these structures resulted in blood pressure fall, bradycardia, vasodilatation in the kidney and the skeletal muscles and also depression of respiration. Similar responses except for a slight tachycardia occurred with application of physostigmine. Application of GABA resulted in a marked attenuation of the reflex vasoconstrictor responses to removal of arterial baroreceptor restraint (carotid occlusion), particularly in the kidney, and to disappearance of the reflex renal vasodilatation to baroreceptor stimulation. The findings suggest that GABA application leads to a general diminution of the tonic vasomotor neuron activity, and with regard to renal vasomotor neurons a virtual cessation. Atropine methylnitrate application induced blood pressure rise, increased peripheral resistance in both skeletal muscle and kidney and a strongly potentiated renal vasoconstrictor response to carotid occlusion. The results indicate that the studied superficial medullary structures play an important role for the maintenance of tonic vasomotor neuron activity, especially renal.
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| 41124. |
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| 41125. |
- Wennergren, Göran, 1947, et al.
(författare)
-
Interaction between the hypothalamic defence reaction and cardiac ventricular receptor reflexes.
- 1976
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Ingår i: Acta physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 96:4, s. 532-47
-
Tidskriftsartikel (refereegranskat)abstract
- The interference with regard to the cardiovascular and gastric motility responses which follows stimulation of the hypothalamic defence area (D.A.) and a simultaneous afferent input from cardiac ventricular receptors was analysed in chloralose-anesthetized cats. In spinalized animals with only the vagal efferent innervation of autonomic effectors from supraspinal structures intact, a D.A. stimulation increased the heart rate to the same level irrespective whether the cardiac receptor afferents were stimulated or not. This suggests that the vagal component of the reflex bradycardia of cardiac receptor origin was completely suppressed by the D.A. stimulation. The reflex gastric relaxation to cardiac receptor activation, mediated via vagal efferent non-adrenergic fibres, was similarly completely blocked by D.A. stimulation. In contrast, the reflex inhibition of the sympathetic outflow to the heart and vessels from cardiac receptors was still effective during a D.A. stimulation, a phenomenon which seems compatible with a simple summation of excitatory D.A. and inhibitory cardiac receptor influences on the sympathetic neurons. The modifying influence from ventricular receptors on D.A. responses closely resembles that exerted by the arterial baroreceptors. The two reflex mechanisms thus work in concert and synergistically with the hypothalamic influences to produce maximal cardiac output and skeletal muscle perfusion without undue increases of pressure load on the pump during a defence reaction.
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| 41126. |
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| 41127. |
- Wennergren, Göran, 1947, et al.
(författare)
-
Studies on the central integration of excitatory chemoreceptor influences and inhibitory baroreceptor and cardiac receptor influences.
- 1976
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 96:1, s. 1-18
-
Tidskriftsartikel (refereegranskat)abstract
- Experiments were performed on cats to explore the integrated cardiovascular responses when excitatory (chemoreceptor) and inhibitory (baroreceptor or cardiac receptor) influences are simultaneously presented to the medullary cardiovascular areas. At a given sinus pressure in the low or medium pressure range, the systemic blood pressure and the vascular resistance were higher when the chemoreceptors were stimulated, while a high, pulsating sinus pressure, i.e.a strong baroreceptor stimulation, could suppress completely even an intense chemoreceptor activation. Thus, the set point and the gain of the baroreflex were increased by a concomitant chemoreceptor activation. These effects are compatible with a simple, mutual 'summation' of excitatory and inhibitory influences on a common population of central vasomotor neurons. The reflex vasodilator effects elicited via vagal cardiac afferents were found to be more effectively suppressed by a concomitant chemoreceptor stimulation than were the baroreceptor effects, provided a primary chemoreceptor response (bradycardia) was at hand, while the heart rate responses were essentially uninfluenced by the prevailing chemoreceptor activity. This chemoreceptor suppression of the reflex vasodilatation from cardiac receptors, which may be of great importance in hypoxic situations, e.g. during a dive, suggests a more complex, neuronal interaction between the two reflex mechanisms in the CNS.
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| 41128. |
- Wennström, Malin, et al.
(författare)
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Cellular localization of p-tau217 in brain and its association with p-tau217 plasma levels
- 2022
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Ingår i: Acta Neuropathologica Communications. - : Springer Science and Business Media LLC. - 2051-5960. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Recent studies highlight phosphorylated tau (p-tau) at threonine tau 217 (p-tau217) as a new promising plasma biomarker for pathological changes implicated in Alzheimer’s disease (AD), but the specific brain pathological events related to the alteration in p-tau217 plasma levels are still largely unknown. Using immunostaining techniques of postmortem AD brain tissue, we show that p-tau217 is found in neurofibrillary tangles (NFTs) and neuropil threads that are also positive for p-tau181, 202, 202/205, 231, and 369/404. The p-tau217, but not the other five p-tau variants, was also prominently seen in vesicles structure positive for markers of granulovacuolar degeneration bodies and multi-vesicular bodies. Further, individuals with a high likelihood of AD showed significantly higher p-tau217 area fraction in 4 different brain areas (entorhinal cortex, inferior temporal gyrus, and superior frontal gyrus) compared to those with Primary age related tauopathy or other non-AD tauopathies. The p-tau217 area fraction correlated strongly with total amyloid-beta (Aβ) and NFT brain load when the whole group was analyzed. Finally, the mean p-tau217 area fraction correlated significantly with p-tau217 concentrations in antemortem collected plasma specifically in individuals with amyloid plaques and not in those without amyloid plaques. These studies highlight differences in cellular localization of different p-tau variants and suggest that plasma levels of p-tau217 reflect an accumulation of p-tau217 in presence of Aβ plaque load.
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| 41129. |
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| 41130. |
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