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Cardiovascular Reflexes (cardiovascular + reflex)
Selected AbstractsEffect of deep brain stimulation of the posterior hypothalamic area on the cardiovascular system in chronic cluster headache patientsEUROPEAN JOURNAL OF NEUROLOGY, Issue 9 2007P. Cortelli The objective of this study was to determine the cardiovascular effects of chronic stimulation of the posterior hypothalamic area (PHA) in cluster headache (CH) patients. Systolic and diastolic blood pressure (SBP, DBP), cardiac output, total peripheral resistance (TPR), heart rate (HR) and breathing were monitored at supine rest and during head-up tilt test (HUTT), Valsalva manoeuvre, deep breathing, cold face test and isometric handgrip in eight drug-resistant chronic CH patients who underwent monolateral electrode implantation in the PHA for therapeutic purposes. Autoregressive power spectral analysis (PSA) of HR variability (HRV) was calculated at rest and during HUTT. Each subject was studied before surgery (condition A) and after chronic deep brain stimulation (DBS) of PHA (condition B). Baseline SBP, DBP, HR and cardiovascular reflexes were normal and similar in both conditions. With respect to condition A, DBP, TPR and the LF/HF obtained from the PSA of HRV were significantly (P < 0.05) increased during HUTT in condition B. In conclusion, chronic DBS of the PHA in chronic CH patients is associated with an enhanced sympathoexcitatory drive on the cardiovascular system during HUTT. [source] Angiotensin AT1 Receptor Antagonist Losartan and the Defence Reaction in the Anaesthetised Rat.EXPERIMENTAL PHYSIOLOGY, Issue 3 2003Effect on the Carotid Chemoreflex Modulation at the level of the nucleus tractus solitarii (NTS) appears to be an effective way of controlling cardiovascular reflexes. Angiotensin II acting on angiotensin AT1 receptors at the central nervous system appears to have an important role in these modulatory processes. The hypothalamic defence area (HDA) is a potential source of descending fibres containing angiotensin II that innervate the NTS. We investigated the effect of AT1 receptor blockade in the NTS on the response to stimulation of HDA in anaesthetised rats treated with the neuromuscular blocking agent pancuronium bromide. The characteristic increase in heart rate, blood pressure and phrenic nerve activity evoked by electrical stimulation of HDA is decreased by the microinjection of the AT1 receptor antagonist losartan into the NTS and the cardiovascular response to carotid body chemical stimulation is also reduced. These results support the hypothesis that AT1 receptors in the NTS play a role in the modulation of cardiovascular reflexes, and modify the influence exerted on the processing of these reflexes by other areas of the central nervous system. [source] Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 84JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2003V Donadio The aim of the study is to determine the site of autonomic lesion in a patient with Holmes-Adie Syndrome (HAS) who subsequently developed generalized anhydrosis. We describe a 38-year-old woman who from age 33 showed a right pupil larger than the left and from age 34 complained of focal and, a year later, generalized anhydrosis. Neurological examination showed absent tendon reflexes and right mydriatic pupil. Brain MRI, EEG, motor and sensory conduction studies were normal. Serologic screening for autoimmune disease was negative. To determine the site of the autonomic lesion the patient underwent the following investigations: pupillary tests with a diluted solution of pilocarpine (0.062%) and adrenaline (0.1%); cardiovascular reflexes; thermoregulatory sweat test (TST); circadian rhythm of body core temperature (CRT°); sympathetic skin response (SSR); microneurography recording of skin sympathetic activity (SSA) from median and peroneal nerves, and muscle sympathetic activity (MSA) from peroneal nerve; skin biopsy to evaluated the eccrine glands. Pupillary tests showed postganglionic parasympathetic and sympathetic denervation only of the right pupil. TST showed complete anhydrosis, SSR and SSA were absent and skin biopsy revealed normal morphology of the eccrine glands with hypotrophy of their structures. These results indicated a lesion of the postganglionic skin sympathetic fibers. Mechanisms for heat loss and conservation, cardiovascular reflexes and MSA were normal excluding a hypothalamic dysfunction or a more diffuse involvement of the autonomic nervous system. In conclusion, our patient showed a HAS associated with generalized anhydrosis and the autonomic investigations suggested underlying postganglionic parasympathetic and sympathetic autonomic lesions. [source] Evidence that 5-hydroxytryptamine7 receptors play a role in the mediation of afferent transmission within the nucleus tractus solitarius in anaesthetized ratsBRITISH JOURNAL OF PHARMACOLOGY, Issue 5 2009Diana Oskutyte Background and purpose:, Central 5-hydroxytryptamine (5-HT)-containing pathways utilizing 5-HT7 receptors are known to be critical for the mediation of cardiovascular reflexes. The nucleus tractus solitarius (NTS) is a site involved in the integration of cardiovascular afferent information. The present experiments examined the involvement of the 5-HT7 receptor in the processing of cardiovascular reflexes in the NTS. Experimental approach:, In anaesthetized rats extracellular recordings were made from 104 NTS neurones that were excited by electrical stimulation of the vagus nerve and/or activation of cardiopulmonary afferents. Drugs were applied ionophoretically in the vicinity of these neurones. Key results:, The non-selective 5-HT7 receptor agonist 5-carboxamidotryptamine maleate (5-CT) applied to 78 neurones increased the firing rate in 18 by 59% and decreased it in 38 neurones by 47%. Similarly, the 5-HT1A agonist 8-OH-DPAT applied to 20 neurones had an excitatory (8), inhibitory (7) or no effect (5) on the 20 neurones tested. In the presence of the 5-HT7 antagonist SB 258719 the 5-CT excitation was attenuated. Furthermore, the excitatory response of NTS neurones evoked by electrical stimulation of the vagus nerve or activation of cardiopulmonary afferents with intra atrial phenylbiguanide was attenuated by SB 258719. The inhibitory action of 5-CT was unaffected by SB 258719 and the 5-HT1A antagonist WAY-100635. WAY-100635 failed to have any effect on 5-CT and vagal afferent-evoked excitations. Conclusions and implications:, Vagal afferent-evoked excitation of NTS neurones can be blocked by SB 258719, a selective 5-HT7 antagonist. This observation further supports the involvement of 5-HT neurotransmission in NTS afferent processing. [source] PHYSIOLOGICAL SLEEP-DEPENDENT CHANGES IN ARTERIAL BLOOD PRESSURE: CENTRAL AUTONOMIC COMMANDS AND BAROREFLEX CONTROLCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 9 2008Alessandro Silvani SUMMARY 1Sleep is a heterogeneous behaviour. As a first approximation, it is subdivided objectively into two states: non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS). 2The mean value and variability of arterial blood pressure (ABP) decrease physiologically from wakefulness to NREMS. In REMS, there may be a further decrease or increase in mean ABP as well as phasic hypertensive events, which enhance the variability of ABP. 3The reduced mean ABP during NREMS results from a decrease in either heart rate or sympathetic vasoconstrictor tone. During REMS, sympathetic activity to the different cardiovascular effectors undergoes a substantial repatterning. Thus, the mean ABP in REMS reflects a balance between changes in cardiac output and constriction or dilatation of different vascular beds. 4In both sleep states, the phasic changes in ABP are driven by bursts of vasoconstriction, which may be accompanied by surges of heart rate. 5The available evidence supports the hypothesis that the sleep-dependent changes in ABP, either tonic or phasic, result from the integration between cardiovascular reflexes and central autonomic commands that are specific to each sleep state. [source] | |||||||||||||||||||