We simultaneously measured pial arteriolar diameter and changes in cortical blood flow during activation of the somatosensory cortex by sciatic nerve stimulation. The pial vasculature was visualized with a closed-cranial window technique in chloralose-anesthetized rats (n = 13). Local blood flow was monitored with laser-Doppler flowmetry. During stimulation of the ...

This article reviews current studies on inner ear blood flow, discusses their relevance to the maintenance of normal homeostasis of the inner ear, reports for the first time clear changes in fundamental properties of cochlear blood flow in the chronic hydropic ear, and describes the potential of applying laser Doppler ...

PURPOSE: To evaluate the possibilities of magnetic resonance imaging (MRI) for quantification of pharmacologically induced changes in optic nerve microcirculation. METHOD: T2-weighted MRI sequences were used to image the eye, optic nerve, and frontal cortex in rats. Two sets of control images before and one set during Gd (DTPA) infusion ...

1. The present investigation explored, in thirty-four anaesthetized cats, the blood flow changes at the optic nerve head elicited by sinusoidally modulated photic stimuli. 2. The stimuli were achromatic, diffuse and had 30 deg diameter field size; the stimulus frequency was varied from 0 to 100 Hz, modulation depth from ...

In order to improve the understanding of the role of sympathetic nerve degeneration in reimplantation failure, the hindlimbs of eight rats (Group I) underwent near-complete amputation. The soft tissues of the hindlimb were transected at the proximal thigh with the femoral artery, vein and femur left intact. The femoral vessels ...

The change of cerebral potential P300 in relation to superior cerebral functions by means of acupuncture stimulation was studied. For this purpose, the parameters of this cerebral response after acupuncture stimulation at acupoints He-7 and LI-4, and at a non-acupuncture control point, have been assessed, both immediately after the stimulation ...

The effect of electrical stimulation of the cervical sympathetic nerve on choroidal blood flow in the cat was investigated. Flow at various sites in 30 pentobarbital-anesthetized cats was continuously measured trans-sclerally using a laser Doppler flowmeter. Changes in either direction, increases and decreases, occurred in response to electrical stimulation of ...

Cadaveric dissections have revealed that accessory blood vessels to the penis often arise near or through the apex of the prostate. These accessory vessels may be easily injured during radical prostatectomy. Increasing attention since the 1980s has focused on preserving potency after radical prostatectomy with a nerve sparing technique. However, ...

Vagal control of pyloric resistance was evaluated in anesthetised pigs by recording gastropyloroduodenal motility and transpyloric flow during emptying of a liquid nonnutrient meal. Vagotomy did not modify pyloric resistance or the characteristics of the flow pulses. Electrical stimulation of the distal stumps of cervical or thoracic vagus nerves decreased ...

The data reviewed in this article suggest that protons should no longer be considered simply as an unwanted by-product of anaerobic respiration that results from either an accumulation of inflammatory cells or a reduced oxygenated blood supply during ischaemia. A fall in extracellular pH can stimulate a subpopulation of sensory ...

Using an X-ray television system, we measured directly changes in the internal diameter (ID), flow velocity, and volume flow of the small pulmonary vessels (100-500 microns ID) in response to electrical sympathetic nerve stimulation (SNS) in anaesthetized cats before and after adrenergic receptor blockade. Flow velocity was obtained by measuring ...

Two mechanisms have been proposed to explain the primary mode of action of sumatriptan: vasoconstriction, and trigeminal nerve terminal inhibition. Sumatriptan is a potent vasoconstrictor of intracranial arteries. It has been shown to increase blood flow velocity in large intracranial arteries in man in a dose-dependent fashion both during and ...

A new technique based on the phenomenon of vascular labelling has been devised for the direct visualisation of overlapping innervation territories of cutaneous nerves. The saphenous, peroneal and sural nerves on one side in anaesthetised rats were exposed, cut centrally and successively stimulated antidromically to induce a neurogenic inflammatory response ...

At least four neural mechanisms influence facial blood flow. Firstly, sympathetic vasoconstrictor fibres exert a tonic constrictor influence on the vasculature of the ears, lips and nose, and sparsely supply other parts of the face. Secondly, the sympathetic nervous system actively dilates the cutaneous vasculature of the face during heat ...

The role of sympathetic regulation in cerebral circulation was studied in the cat by continuous measurement of cerebral tissue oxygen tension (BrPO2), carbon dioxide tension (BrPCO2), pH(BrpH) and blood pressure. The ipsilateral superior cervical ganglion was electrically stimulated for 3 min. A slight decrease in BrPO2 and a slight but ...

Activation of perivascular parasympathetic nerves enhances cerebral blood flow. In the present experiments, functional aspects of this flow regulating capacity were investigated. It was found that parasympathetic nerve stimulation does not facilitate the normalization of the cerebral blood flow reduced by sympathetic stimulation. In contrast, activation of sympathetic nerves may ...

Stimulation of cerebrovascular parasympathetic nerves markedly increases cortical blood flow. Nitric oxide (NO) or a NO containing compound is present in these nerves, and its release may therefore be partly responsible for the flow increase. In addition, transmitters released from the nerves may cause synthesis and release of this compound ...

The aim of this study was to determine the distribution within the whole brain of the vascular effects of stimulation of the substantia innominata. This basal forebrain nucleus is the major cholinergic input in the neocortex in the rodent. The local cerebral blood flow was measured by the autoradiographic [14C]iodoantipyrine ...

The present study was designed to study the localization and effects of some VIP-related peptides on the cerebral circulation in cats. A rich supply of nerve fibres containing vasoactive intestinal peptide- (VIP) was seen. Nerve fibres containing pituitary adenylate cyclase activating peptide and helospectin-like immunoreactivity (-IR) were moderate in numbers ...

The neural regulation of the bronchial vasculature differs from that of the general systemic circulation in that vasodilator reflexes play a major part in determining blood flow. These reflexes originate in the upper or lower airways, in carotid chemoreptors or in cardiac chemosensitive nerves; those arising in the lower airways ...

The laterodorsal tegmental nucleus (LDT) is the largest aggregation in the brainstem of cholinergic neurons whose axons reach the thalamus as part of a diffuse projection to the forebrain. We measured the regional blood flow in the thalamus by means of laser Doppler flowmetry, and examined whether the blood flow ...

We examined the effects of aldose reductase inhibition on nerve biochemistry and function, blood flow and endoneurial oxygenation in experimental diabetes mellitus. After 1 month untreated diabetes in rats, treatment with the novel sulphonylnitromethane aldose reductase inhibitor, ZENECA ZD5522, prevented a progressive increase in sciatic nerve resistance to hypoxic conduction ...

In previous work, we suggested that there were differences in vasoregulation between dorsal root ganglia (DRG) and the endoneurium of peripheral nerve trunks. To investigate sympathetic control of both microvessel beds, we compared local perfusion in the sciatic nerve endoneurium and lumbar DRG of adult Sprague-Dawley rats treated from neonatal ...

There is a considerable body of evidence to suggest that activation of vasodilator fibers in the parasympathetic facial (VIIn) nerve can increase cerebral blood flow. The changes seen with VIIn stimulation raise the question as to whether they occur independent or in parallel with changes in cerebral metabolism. In these ...

Cerebral vascular changes seem to play a fundamental role in the pathogenesis of various functional disturbances, (i.e. those suggested for migraine pathogenesis). However the exact role of single regulatory aspects (metabolic-neuronal-mechanic) are not completely understood and easily investigated in man. In particular, the role of autonomic nervous system is widely ...

To better understand the mechanisms of local anesthetic-reduced nerve blood flow and nerve blood flow regulation, the effects of cocaine on blood flow and vasoactive prostaglandins were tested in the sciatic nerve of anesthetized rats. After 30 min, nerve blood flow was significantly reduced from baseline by perineural injection of ...

Neuropeptide Y, NPY, is one of the most common neuropeptides in mammalian and seems to influence many physiological systems significantly, e.g. the cardiovascular system and the gastrointestinal system. In the present investigation the distribution, localization and physiological effects of NPY were studied in the mammalian genital tract, primarily the female. ...

Animal models of peripheral nerve ischemia have yielded variable results. The question of whether post-ischemia re-establishment of blood flow to the nerves augments injury has not been examined. To study this question, the ipsilateral common iliac and femoral arteries were occluded with arterial snares for 3 hours in rats; 14C-butanol ...

Whereas the anatomy of the vasculature supplying the intratemporal facial nerve is well known, little is known of the dynamics of blood flow within the nerve. The present study was performed to ascertain whether laser Doppler flowmetry (LDF) could detect changes in blood flow within the tympanic segment of the ...

The effect of vasodilation on simultaneously measured interstitial fluid pressure (IFP, micropuncture) and blood flow (laser-Doppler) in the low compliant pulpal connective tissue was investigated in 10 cats. Vasodilation was induced by electrical stimulation of the tooth after pretreatment with the sympathetic blocker guanethidine. Visualization of the sensory neuropeptides calcitonin ...

There is evidence that adrenal blood flow may be regulated in part by neuropeptides released from the capsular region of the adrenal gland in response to splanchnic nerve stimulation. The present study investigated the effects of various neuropeptides on the rate of perfusion medium flow through an intact in situ ...

The effects of sympathetic beta-agonists on blood pressure and cochlear blood flow were studied in 15 guinea pigs. Cochlear blood flow was measured by a laser Doppler flowmeter, Periflux PF2 (Perimed, Sweden). Small doses (0.01 and 0.1 microgram/kg) of isoproterenol elevated blood pressure, but larger doses (10 and 50 micrograms/kg) ...

BACKGROUND AND PURPOSE: Although transcutaneous electrical nerve stimulation (TENS) has been used clinically for more than 20 years, the hemodynamic effects of this intervention remain controversial. Our goal was to determine the effects of high-frequency TENS on calf blood flow in healthy subjects. SUBJECTS: Four men and seven women ranging ...

BACKGROUND: With percutaneous recordings of muscle nerve sympathetic activity (MSA), it is possible to study interactions between the autonomic nervous system and anesthetics. This study describes the effects of propofol infusion both before and during microlaryngoscopy. METHODS: Nine patients participated. MSA was recorded, muscle and skin blood flows were measured. ...

Euglycemic hyperinsulinemia stimulates both sympathetic nerve activity and blood flow to skeletal muscle, but the mechanism is unknown. Possible mechanisms that may stimulate muscle blood flow include neural, humoral, or metabolic effects of insulin. To determine whether such insulin-induced vasodilation is modulated by stimulation of adrenergic or cholinergic mechanisms, we ...

Capsaicin-induced microcirculatory changes in the cochlea of anaesthetized guinea pigs were examined by laser-Doppler flowmetry. Close intraarterial capsaicin infusion into the anterior inferior cerebral artery at doses of 10-50 pmol/min was followed by dose-dependent vasodilatation. Capsaicin infused in a dose of 150-200 pmol/min or above resulted in vasoconstriction in the ...

The hydrogen clearance technique of blood flow measurement often yields biexponential washout curves. In peripheral nerve, arteriovenous shunt vessels may clear hydrogen gas, causing the fast component of a biexponential curve. We simulated the washout of hydrogen from nerve tissue in the vicinity of a large shunt vessel by modeling ...

Two chemically distinct aldose reductase inhibitors, ponalrestat and tolrestat, were tested against laser Doppler blood flow and conduction deficits in the sciatic nerve of diabetic rats. The effects of two months of streptozotocin-induced diabetes and aldose reductase inhibition on body weight, plasma glucose, and nerve sugars and polyols were comparable ...

The effects of non-noxious and noxious mechanical stimulation of the skin on cytotoxic activity of splenic natural killer (NK) cells and splenic blood flow were examined in anesthetized rats. Bilateral brushing of the body surface between the lateral chest and hindlimb for 30 min did not significantly influence cytotoxic activity ...

An enhanced understanding of the microcirculation and blood flow in glaucoma is needed. Definitive study has been impaired by lack of a quantitative and objective clinical method to measure human optic nerve and peripapillary choroidal blood flow. Through optical sectioning of the optic nerve head and peripapillary retina, confocal scanning ...

1. In chloralose-urethane anaesthetized cats, the dorsal cardiovascular reactive area (DCRA) in the parvocellular reticular nucleus dorsomedial to the facial nucleus, and the ventral cardiovascular reactive area (VCRA) ventromedial to the facial nucleus, were stimulated by microinjections of sodium glutamate (100-200 nmol) or electric current. 2. Stimulation of DCRA, with ...

We analyzed in the forearm of "comfortably warm" male volunteers 1) reflex sympathetic vascular resistance changes evoked by short-term graded [1.5-min exposure to 15, 40, 55, and 70 mmHg and high and barely tolerated (77-95 mmHg)] lower body negative pressure (LBNP) and 2) resistance changes evoked by abolition of control ...

We tested the action of intraperitoneal sumatriptan, a 5-HT1D receptor agonist that aborts migraine headaches, using a model of neurogenic inflammation induced by capsaicin applied to the rat sciatic epineurium. Sumatriptan prevented the development of capsaicin-induced hyperemia without inducing pretreatment vasoconstriction or altering AV shunt flow. The findings indicate that ...

Evidence is presented that the rate of inward diffusion of chemicals through exposed dentine is affected by the rate of outward flow of fluid through the dentinal tubules. Such a flow has been demonstrated in cats. The flow rate appears to depend upon the pulpal tissue-fluid pressure; flow increased during ...

The purpose of this study was to investigate if painful stimulation produces blood flow changes in the tooth pulp and the facial skin in humans. Also, we attempted to find out if the possible blood flow changes induced by painful stimulation could be explained by central sympathetic and parasympathetic reflex ...

Mechanisms of capsaicin-induced vascular changes were examined in the nasal mucosa of anesthetized adult rats. Intra-arterial infusions of capsaicin at doses of 20-100 pmol/min into the external carotid artery resulted in a dose-dependent increase in nasal blood flow as assessed by laser-Doppler flowmetry. Intra-arterial infusion of ruthenium red (RR, 2.5-10 ...

Experiments were performed to investigate, in the normal and acutely inflamed rabbit knee joint, the role of prostaglandins in the regulation of joint blood flow, measured by laser Doppler flowmetry, as well as their modulation of sympathetic vasoconstriction. Close intra-arterial injection of prostaglandin E2 (PGE2) produced a dose-dependent vasodilatation in ...

Pelvic organs have triple innervation from the pelvic, sympathetic and pudendal nerves. Peripheral effects can be studied by neurostimulation of the nerves, whereas the topography of the spinal cord neurons can be determined by horseradish peroxidase tracing. We have evaluated the neurophysiologic effects of the nerves at their target organs ...

The changes in conductivity of skeletal muscle vessels of the hind leg and tissue-type plasminogen activator (t-PA) activity in outflowing blood after electrostimulation (5 V, 0.5 ms, 20 Hz, 30 s) at the L4-L5 level of the peripheral end of the transected isolated sympathetic chain were studied in experiments on ...

Hemodynamic and autonomic mechanisms underlying the cardiovascular defense reaction elicited by electrical stimulation of the dorsolateral periaqueductal gray region were evaluated in pentobarbital sodium-anesthetized Sprague-Dawley rats. Stimulation of this area produced transient increases in mean arterial pressure and more sustained increases in heart rate, hindlimb blood flow, and plasma catecholamine ...