Carotid Body Tumor ; surgery ; Humans ; Hypertension ; Pressoreceptors

Graded infusion and bolus injection methods of vasoactive drugs have both been used to measure baroreflex sensitivity. To determine whether the two methods produce the same values of baroreceptor sensitivity, phenylephrine and nitroglycerin was administered intravenously by both graded infusion and bolus injection methods to 11 rabbits. To evaluate the baroreflex control of heart rate(HR), a logistic sigmoid function model was used. The range of HR and baroreflex gain by the bolus method(100.53+/-0.62, 0.113+/-0.011) were significantly(p<0.05) larger than those measured by the graded infusion method(108.49+/-1.66, 0.126+/-0.013). However, there were no significant changes in the pressure at the midrange of the baroreflex curve. Thus my results indicate that baroreflex control of HR by the graded infusion and bolus injection methods is not equivalent and that baroreflex-induced HR response to a gradual change in pressure is less than that seen with a repid change.
Baroreflex* ; Colon, Sigmoid ; Heart ; Heart Rate ; Nitroglycerin ; Phenylephrine ; Pressoreceptors ; Rabbits*

Hemodynamic depression (hypotension and bradycardia) can occur during or after carotid angioplasty and stenting (CAS) due to stretching of the baroreceptors in the carotid sinus. The predisposing factors of hemodynamic depression have not been reported previously. In general, hemodynamic depression after CAS may continue for up to 3-5 days, but disappears within 7 days. We report herein a 65-year-old man with severe hemodynamic depression after sequential CAS, and discuss the possible causes from an anatomical point of view.
Aged ; Angioplasty ; Carotid Sinus ; Depression ; Hemodynamics ; Humans ; Pressoreceptors ; Stents

BACKGROUND AND OBJECTIVES: Central role of the vestibular system on control of blood pressure and interrelationships between the vestibular nucleus and solitary nucleus during acute hypotension were investigated in bilateral labyrinthectomized (BLX) or sinoaortic denervated (SAD) rats. Changes of electrical activity in the medial vestibular nucleus (MVN), solitary tract nucleus (STN), and rostral ventrolateral medullary nucleus (RVLM) were investigated in rats in while acute hypotension was induced by sodium nitroprusside (SNP). RESULTS: Evoked potential in MVN neuron caused by electrical stimulation of the peripheral vestibular system was composed of 3 waves with latencies of 0.48+/-.10 ms, 1.04+/-.09 ms and 1.98+/-.19 ms. Electrical stimulation to MVN or RVLM increased blood pressure. MVN at the induction of acute hypotension showed excitation in 61% of type I neurons and inhibition in 68% of type II neurons. In STN, acute hypotension produced excitation in 62.1% of neurons recorded in intact labyrinthine animals, inhibition in 72.3% of neurons recorded in BL animals, and excitation in 60% of recorded neurons in SAD animals. In RVLM, acute hypotension produced excitation in 66.7% of neurons recorded in intact labyrinthine animals and inhibition in 64.9% of neurons recorded in BL animals. In spatial distribution of STN neurons responded to acute hypotension, excitatory responses were mainly recorded in rostral and ventral portion, and inhibitory responses were mainly recorded in caudal and lateral portion. In RVLM, excitatory responses were mainly recorded in rostral and dorsomedial portion, and inhibitory responses were mainly recorded in caudal and ventrolateral portion. CONCLUSION: These results suggest that afferent signals from the peripheral vestibular receptors are transmitted to STN through the vestibular nuclei and assist to the baroreceptors for controlling blood pressure following acute hypotension.
Animals ; Blood Pressure* ; Electric Stimulation ; Evoked Potentials ; Hypotension* ; Neurons ; Nitroprusside ; Pressoreceptors ; Rats* ; Solitary Nucleus ; Vestibular Nuclei

OBJECTIVE: The electric analog circuit model can be used to analyse the various function of the cardio vascular system and the dynamic characteristics on each part of human body. According to the previous studies, viscous resistance, flow inertia, and vascular compliance in the cardiovascular system are analogous to resistance, inductance, and capacitance in electric circuit, so the cardiovascular system models have been represented by the electric circuit models. These approaches were to propose suitable models for the interested part of body and to simulate the various characteristics on the cardiovascular system. METHODS: This paper tried to put the characteristics of morphologic structure into the suggested electric circuit model. After setting parameter values of the model the dynamic characteristics of the cardio vascular system is simulated using VisSim, which is one of the simulation tools. RESULTS: The derived simulation results have represented major cardiovascular functions of normal adults. Also simulation results reflect the variation due to the pathophysiological state. CONCLUSION: The controller by baroreceptor, which is one of controllers to control the cardiovascular system, is appended in the model. The dynamic response characteristics and the procedure to restore blood pressure to normal state was observed by simulation lasted a certain period of bleeding.
Adult ; Blood Pressure ; Cardiovascular System* ; Compliance ; Hemorrhage ; Human Body ; Humans ; Pressoreceptors

A study has been made of efferent single fibers in the cat whose axon is projected to the cardiac branches of the right vagus. The main objective of this experiment was to replicate some of the mechanisms involving vagal efferent discharges and to observe the effect of somatic stimulation, pain and coldness, on the discharges. Electrical activities of a single of a single fiber were recorded on the central segments of small cut strands separated from the right cervical vagus under the pentobarbital sodium anesthesia. The fiber was considered to be cardio-inhibitory in function because of the activity in inverse effect on the heart rate in almost all conditions. Pain and cold stimulation of skin reflexly excited these fibers, as did stimulation of baroreceptor in the carotid sinus. Response to the somatic stimulation applied on the skin, by the increase of impulse frequency, amplitude, discharge duration and pulse rate of electrical discharges were observed. The auther observed that efferent fibers in the cutaneous nerve excited the cardiac efferent vagal fibers in response to reflex stimulation.
Anesthesia ; Animals ; Axons ; Carotid Sinus ; Cats ; Heart Rate ; Nerve Fibers, Myelinated ; Pentobarbital ; Pressoreceptors ; Reflex ; Skin

The Shy-Drager syndrome is a very rare chronic progressive disease characterised by autonomic failure and multiple system atropy. The main clinical manifestations of this syndrome are orthostatic hypotension, urinary and bowel dysfunction, impaired sexual potency and parkinsonean symptoms. A key in the management of anesthesia is the maintenance of cardiovascular atability. These patient are suffered from defective baroreceptor regulation of the blood pressure as a result of autonomic failure. We report a successful epidural anesthesia for vwicolithotomy in a female patient with Shy-Drager syndrome.
Anesthesia ; Anesthesia, Epidural ; Blood Pressure ; Female ; Humans ; Hypotension, Orthostatic ; Pressoreceptors ; Shy-Drager Syndrome

The Shy-Drager syndrome is a very rare chronic progressive disease characterised by autonomic failure and multiple system atropy. The main clinical manifestations of this syndrome are orthostatic hypotension, urinary and bowel dysfunction, impaired sexual potency and parkinsonean symptoms. A key in the management of anesthesia is the maintenance of cardiovascular atability. These patient are suffered from defective baroreceptor regulation of the blood pressure as a result of autonomic failure. We report a successful epidural anesthesia for vwicolithotomy in a female patient with Shy-Drager syndrome.
Anesthesia ; Anesthesia, Epidural ; Blood Pressure ; Female ; Humans ; Hypotension, Orthostatic ; Pressoreceptors ; Shy-Drager Syndrome

This study was Uesigned to evaluate the reflexive heart rate response to acute blood loss during sodium nitroprusside and prostaglandin E1 induced-hypotension in isoflurane anesthetized dogs. The results were as follows: 1) Reflexive increase in heart rate during induced hypotension was significantly greater in sodium nitroprusside than prostaglandin E1. 2) Reflexive increase in heart rate during induced hypotension was significantly greater prostaglandin E1 induced-hypotension than during that wih sodium nitroprusside. From these results, it suggest that prostaglandin E1 induced-hypotension provides a safer margin than with sodium nitroprusside when rapid bleeding occurs during anesthesia and surgery.
Alprostadil ; Anesthesia ; Animals ; Baroreflex* ; Dogs ; Heart Rate ; Hemorrhage ; Hypotension* ; Isoflurane ; Nitroprusside* ; Pressoreceptors* ; Reflex ; Sodium*

This study was Uesigned to evaluate the reflexive heart rate response to acute blood loss during sodium nitroprusside and prostaglandin E1 induced-hypotension in isoflurane anesthetized dogs. The results were as follows: 1) Reflexive increase in heart rate during induced hypotension was significantly greater in sodium nitroprusside than prostaglandin E1. 2) Reflexive increase in heart rate during induced hypotension was significantly greater prostaglandin E1 induced-hypotension than during that wih sodium nitroprusside. From these results, it suggest that prostaglandin E1 induced-hypotension provides a safer margin than with sodium nitroprusside when rapid bleeding occurs during anesthesia and surgery.
Alprostadil ; Anesthesia ; Animals ; Baroreflex* ; Dogs ; Heart Rate ; Hemorrhage ; Hypotension* ; Isoflurane ; Nitroprusside* ; Pressoreceptors* ; Reflex ; Sodium*