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Biomedical subjects

C Kennedy

Publications and source records attributed to C Kennedy.

At least 127 records · Page 7Linked to original sources
PubMed1996

ATP as a co-transmitter with noradrenaline in sympathetic nerves--function and fate.

ATP and noradrenaline are co-stored in synaptic vesicles in sympathetic nerves and when co-released act postjunctionally to evoke contraction of visceral and vascular smooth muscle. In the original purinergic nerve hypothesis it was proposed that ATP would then be sequentially broken down to ADP, AMP and adenosine. Although such breakdown can be measured, it is not clear how the time-scale of breakdown compares with the time-course of the postjunctional actions of ATP. We have investigated the role of ectoATPase in modulating purinergic neurotransmission in the guinea-pig vas deferens using ARL67156 (formerly FPL67516), a recently developed inhibitor of ectoATPase. ARL67156 (1-100 microM) potentiated neurogenic contractions in a concentration-dependent manner. Onset of potentiation was rapid and the effect reversed rapidly on washout of the drug. The effect was also frequency dependent, being greater at lower frequencies. The purinergic component of the neurogenic contraction was isolated using the alpha 1 antagonist prazosin (100 nM) and ARL67156 caused a similar potentiation. ARL67156 also potentiated contractions evoked by exogenous ATP (100 microM), but had no effect on those of the stable analogue alpha, beta-methylene ATP (500 nM). In the presence of the P2 purinoceptor antagonist PPADS (100 microM), ARL67156 also had no effect on contractions evoked by noradrenaline (10 microM) or KCI (40 mM). These results are consistent with an inhibitory action of ARL67156 on ectoATPase and suggest that ectoATPase modulates purinergic transmission in the guinea-pig vas deferens. When released from sympathetic nerves, ATP acts at the P2X purinoceptor, a ligand-gated cation channel, to evoke depolarization and contraction. In single acutely dissociated smooth muscle cells of the rat tail artery, studied under voltage-clamp conditions, ATP and its analogues evoke an inward current, with a rank order potency of 2-methylthioATP = ATP > alpha, beta-methylene ATP. This is very different from the order of potency for evoking contraction in whole vessel rings, which is alpha, beta-methylene ATP > > 2-methylthioATP > or = ATP. This discrepancy can be explained by a previously unrecognized attenuation of the action of ATP and 2-methylthioATP, but not alpha, beta-methylene ATP, by ectoATPase in whole tissues.

Adenosine Triphosphatases↗
PubMed1996

Visually guided reaching with the forelimb contralateral to a "blind" hemisphere in the monkey: contribution of the cerebellum.

Metabolic activity was mapped in the cerebellar cortex and its major inputs and projection targets in monkeys performing visually guided reaching with the left forelimb. Normal monkeys and monkeys deprived of visual input to the right cerebral hemisphere by right optic tract section, combined in some cases with forebrain commissurotomy, were studied. We reported previously that visually guided reaching with the left forelimb activated the motor cortex of the right hemisphere equally in all these monkeys, indicating that reaching was controlled by the right hemisphere whether it was visually intact or "blind" [Savaki H.E. et al. (1993) J. Neurosci. 13, 2772-2789]. In the present study, metabolic activations were observed in the left cerebellar hemispheric extensions of vermian lobules V, VI and VIII, again regardless of whether the right hemisphere was visually intact or "blind". In intact monkeys, however, the activations were significantly smaller in the lateral than in the paravermal zone of these hemispheric extensions, whereas in tractotomized/commissurotomized monkeys the activations were equal in the two zones. The greater activations in the left lateral zone in tractotomized/commissurotomized monkeys may represent compensation in part for the visual deafferentation of the right cerebral hemisphere. Also observed were metabolic activation in the left dorsolateral pontine nucleus in tractotomized/commissurotomized monkeys and metabolic depression in the left dentate nucleus in visually intact monkeys. This pattern of results suggests the following conclusions. The activated loci in the left cerebellar cortex combine (i) visual information about the target relayed by seeing cerebral hemispheres, and (ii) sensorimotor information concerning intended and actual movements of the left forelimb relayed by the right cerebral hemisphere and the limb, respectively, and then (iii) send this integrated information back to the motor cortex of the right cerebral hemisphere, thus enabling it to guide the left forelimb to the target whether the hemisphere is visually intact or "blind".

Animals↗
PubMed1996

A comparison of hemolysis rates using intravenous catheters versus venipuncture tubes for obtaining blood samples.

OBJECTIVE: The primary purpose of this study was to compare the rate of hemolysis in blood samples obtained by an i.v. catheter versus the rate in samples obtained by venipuncture (Vacutainer tubes and needles; Becton Dickinson Vacutainer Systems, Franklin Lakes, N.J.). Subsequently, variance in i.v. catheter diameter was reviewed to determine its influence on hemolysis rate of i.v. catheter aspirate. DESIGN: A randomized, prospective study was used to evaluate hemolysis differences between the two blood sampling methods. A descriptive, retrospective review of study data was used to evaluate the importance of the variable i.v. catheter diameter. METHODS: The study group consisted of patients who came to the emergency department and required both an i.v. infusion and blood sampling for determination of electrolyte levels and complete blood cell count. Pediatric patients (younger than 16 years) were excluded. The ED patients who qualified for the study were randomly assigned to either group A or B. The blood samples for patients in the A group were obtained through the i.v. catheter at the time of insertion. The i.v. catheters ranged in size from 24 gauge to 14 gauge. Patients in the B group also had insertion of an i.v. line, but their blood samples were obtained by Vacutainer venipuncture at a separate site. The Vacutainer needle was standardized at 21 gauge. All blood samples were collected by one of seven experienced ED nurses. The nurse who collected the blood sample for an study patient was responsible for result follow-up. RESULTS: A total of 165 patients participated in the study; 87 patients were assigned to the A (i.v.) group, and 78 patients participated in the B (venipuncture) group. In group A a total of 12 of 87 (13.7%) blood samples hemolyzed. Hemolysis occurred in 3 of 78 (3.8%) of group B samples. These findings were statistically significant (p < 0.05). When we examined the variable i.v. catheter diameter, we noted a lower incidence of hemolysis with larger catheter diameters: 24 gauge (100%), 22 gauge (25%), 20 gauge (15%), 18 gauge (10%), 16 gauge (0%), 14 gauge (0%). This findings was statistically significant (p < 0.05). CONCLUSIONS: Hemolysis of blood samples obtained by an i.v. catheter was significantly higher than when blood was obtained through Vacutainer venipuncture. There is an inverse correlation between i.v. catheter diameter and the rate of hemolysis.

Blood Specimen Collection↗
PubMed1996

Does the NAIP classification predict length of stay in rehabilitation, geriatrics and palliative care?

The Australian National Non-Acute Inpatient Project (NAIP) reported its findings on casemix in rehabilitation and slow stream geriatric medicine in October 1992. It proposed a per diem NAIP classification of 19 classes using six major clinical groups and the resource utilisation groups version three activities of daily living index (RUG III ADL index). Weightings were determined based on time spent by clinical staff in treating these patients. A quality management study was undertaken in the rehabilitation, geriatrics, and palliative care wards of the Illawarra Area Health Service for three months in 1993, analysing length of stay and cost against the predictive weights of the NAIP classification. The study concluded that this classification was an acceptable predictor of per diem costs of care in these wards of the Illawarra but was not a good predictor of length of stay.

Activities of Daily Living↗
PubMed1996

An assessment of lower back pain in young adults: implications for college health education.

A convenience sample of 243 undergraduates completed a 36-item questionnaire on their knowledge about back care and exercise patterns before they attended lectures and a workshop on back mechanics. At the workshop, the students were individually evaluated for posture, hamstring flexibility, hip flexor flexibility, back and abdominal strength, and lifting technique. Twenty-nine percent of the students reported that they experienced no back pain; 71% experienced lower back pain 1 to 5 days a week. The majority were neglectful of their posture, lifting and carrying techniques, and scored fair-to-poor on the hamstring flexibility test, possibly foreshadowing back problems in later life. The majority of respondents were unsure of what exercises to do for back care. Within the subgroup of students who claimed they were knowledgeable about exercise, more than 50% were performing ineffective and potentially harmful exercises. The results underscored the potential worth of health education on back care offered through didactic instruction and experiential workshops.

Adult↗
PubMed1996

Outpatient laparoscopic cholecystectomy feasibility.

One-hundred nineteen elective cholecystectomies were performed at Kern Medical Center over a 20-month period from October 1992 to May 1994 and were retrospectively reviewed. Eight males and 111 females ranged in age from 16 to 70. Laparoscopic cholecystectomy was attempted in 116 patients and converted to open in 8 (7%). Of the elective procedures, 108 (91%) were planned as outpatient procedures. Of the 108 planned outpatient procedures, 73 (68%) were successfully completed as outpatients. Of the 35 patients who required unplanned admission, 21 were discharged in less than 24 h. In total, 101 (87%) of the 116 elective cholecystectomies begun laparoscopically were discharged in less than 24 h. Subsequent to this data analysis, our institution is developing a 23.9 h "day hospital" for postanesthesia observation. With extended postoperative monitoring and observation, patients with short-term problems such as nausea, vomiting, pain, and even patients with medical conditions requiring close observation and control should be able to avoid admission. This retrospective study indicates that with development of a 23.9 h postanesthesia care unit, the majority of elective cholecystectomies can be attempted and completed laparoscopically on an outpatient basis.

Adolescent↗
PubMed1996

Investigation of a multiyear multiple critical care unit outbreak due to relatively drug-sensitive Acinetobacter baumannii: risk factors and attributable mortality.

From 1990 to 1993, an outbreak of respiratory Acinetobacter baumannii infection occurred in five intensive care units (ICUs) of a tertiary care center. A. baumannii was subsequently isolated from disinfected temperature probes and ventilator circuits. Pulsed-field gel electrophoresis suggested that a single strain accounted for 93% of patient isolates and 88% of environmental isolates. Univariate risk factors for A. baumannii acquisition were tracheostomy (P < .01), ventilation >3 days (P < .01), dialysis (P = .03), Stenotrophomonas maltophilia respiratory colonization (P = .02), parenteral nutrition (P = .05), and enteric feeding (P < .01). Logistic regression analysis showed duration of ventilation and enteric feeding to be independent risk factors. The outbreak strain was relatively antibiotic-susceptible, but the mortality attributable to respiratory A. baumannii acquisition was 23%. Only the APACHE II score was independently associated with increased mortality. Multifaceted control measures, including gas sterilization of temperature probes, terminated the outbreak.

Acinetobacter Infections↗
PubMed1996

Mammographically negative breast cancer at the Strathfield Breast Centre.

BACKGROUND: The current diagnostic modalities used to detect breast cancer are mammography, together with clinical examination, ultrasound and fine needle aspiration biopsy (FNAB). The accuracy rates for each modality varies and a combination of the modalities is recommended to detect cancer early. Some authors have suggested that mammography should be used primarily as a screening tool because of the false negative mammography results that have been reported in the past 10 years. The records of patients at the Strathfield Breast Centre were reviewed to determine the accuracy of other modalities. METHODS: The records of 371 breast cancer patients treated at the Strathfield Breast Centre in the 6 years form 1989 to 1994 were reviewed to determine the accuracy of mammography, ultrasound, clinical examination and fine needle aspiration biopsy. Of the 371 women with histopathologically diagnosed breast cancer, 349 had mammography. RESULTS: The accuracy rate of mammography in the present study was 91% with a false negative rate of 9%. It was found that there was no significant delay in treatment of breast cancer in mammogram-negative patients. CONCLUSIONS: Mammographically negative breast cancer was found to be more common in younger women, to be similar in size to mammogram-positive cancer, to occur in all histological types and grades and was usually invasive rather than noninvasive. The rate of lymph node involvement was similar to the mammogram-positive group.

Adult↗
PubMed1996

ATP as a cotransmitter in perivascular sympathetic nerves.

1. P2X-receptors are ligand-gated ion channels which activate within milliseconds of agonist binding, causing rapid cellular depolarization and excitation. This makes them ideally suited to mediate the rapid neurotransmitter functions of adenosine 5'-triphosphate (ATP). 2. The initial postjunctional response of the vas deferens and most blood vessels to sympathetic nerve stimulation is a rapid, transient excitatory junction potential (EJP). With sufficient stimulation EJPs summate and the membrane depolarizes sufficiently to open voltage-dependent calcium channels, initiating a calcium action potential and contraction. 3. EJPs are inhibited by desensitization of the P2X-receptor by the stable agonist alpha, beta-methyleneATP (alpha, beta-meATP) and by the P2X-receptor antagonists ANAPP3, suramin and pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid, indicating that they are consequent upon activation of the P2X-receptor. 4. The P2X-receptor was originally defined by contractile studies in smooth muscle preparations, where a rank order of agonist potency of alpha, beta-meATP > > 2-methylthioATP (2-meSATP) > or = ATP was found. However, recent results show that the potency of ATP and 2-meSATP, but not alpha, beta-meATP, is decreased by 100-to 1000-fold by breakdown and when this is prevented, ATP and 2-meSATP are more potent than alpha, beta-meATP as agonists at the P2X-receptor. 5. This conclusion was supported by the cloning and functional expression of the P2X1-receptor from the rat bladder. A total of seven P2X-subunits have since been cloned and the P2X1-subunit is thought to be the predominant subunit expressed in vascular smooth muscle cells.

Adenosine Triphosphate↗
PubMed1996

Enhancement of sympathetic purinergic neurotransmission in the guinea-pig isolated vas deferens by the novel ecto-ATPase inhibitor ARL 67156.

1. Field stimulation of the sympathetic nerves of the guinea-pig isolated vas deferens with trains of pulses of 20 s at 1-8 Hz produced characteristic biphasic contractions. The effect of the novel ecto-ATPase inhibitor, 6-N,N-diethyl-D-beta, gamma-dibromomethyleneATP (ARL 67156, formerly known as FPL 67156), on the magnitude of the initial, predominantly purinergic peak of this response was studied in order to determine the influence of enzymatic degradation of adenosine 5'-triphosphate (ATP) on its action as a neurotransmitter. 2. The peak magnitude of the response to nerve stimulation was significantly increased in a concentration-dependent manner by ARL 67156 (5-100 microM) and the size of the neurogenic response at 4 Hz was approximately doubled in the presence of ARL 67156 (100 microM). 3. ARL 67156 (100 microM) has a rapid onset of action. The enhancing effect on neurogenic contractions was maximal after 10 min, was well maintained for at least 30 min and was rapidly reversed, with responses returning to control levels 10 min after washout. 4. The neurogenic contraction in the presence of prazosin (0.1 microM) was purely purinergic, as it was abolished by the P2-purinoceptor antagonist, PPADS (100 microM). ARL 67156 (100 microM) produced a similar degree of enhancement of neurogenic responses in the absence and presence of prazosin, supporting the view that the enhancing effects of ARL 67156 on neurogenic contractions result from potentiation of the action of ATP. 5. Exogenous ATP and alpha, beta-methyleneATP produced rapid transient contractions. Responses to ATP were increased in magnitude and duration in the presence of ARL 67156 (100 microM), whereas those to the stable analogue, alpha, beta-methylene ATP were not significantly affected. 6. Contractions to exogenous noradrenaline (10 microM) and KCl (40 mM) were significantly enhanced by ARL 67156 (100 microM), but this potentiation was abolished by PPADS (100 microM). Therefore, this effect of the ecto-ATPase inhibitor may be due to a build up of endogenous ATP, increasing the sensitivity of the smooth muscle to other agonists. 7. It is concluded that ARL 67156 potentiates the action of ATP, and that when ATP acts as a neurotransmitter its postjunctional actions are greatly attenuated by enzymatic degradation.

Adenosine Triphosphatases↗
PubMed1996

Characterization of a P2X-purinoceptor in cultured neurones of the rat dorsal root ganglia.

1. The electrophysiological actions of the P2-purinoceptor agonists, adenosine 5'-triphosphate (ATP), 2-methylthio ATP (2-meSATP) and alpha, beta-methyleneATP (alpha, beta-meATP) and of uridine 5'-triphosphate (UTP) were studied under concentration and voltage-clamp conditions in dissociated neurones of 1-6 day old rat dorsal root ganglia. 2. ATP (10 nM-100 microM) applied rapidly via a U-tube perfusion system (equilibration time < 10 ms) activated concentration-dependent inward currents with a latency to onset of a few ms, an EC50 of 719 nM and a Hill slope of 1.47. 3. 2-meSATP (10 nM- 100 microM) and alpha, beta-meATP (100 nM - 100 microM) also evoked transient inward currents. The EC50 and Hill slopes were 450 nM and 1.58 for 2-meSATP and 1.95 microM and 1.53 for alpha, beta-meATP respectively. There was no significant difference between the maximum currents evoked by the three agonists. 4. As the concentration of ATP increased so the rate of rise and decay of the currents also increased. At 100 and 300 nM ATP the decay of the current was best fitted by a single exponential, but at 1 microM and above two exponentials were required. Log-log plots of the rise time or time constants of decay versus concentration were linear. Currents evoked by 2-meSATP and alpha, beta-meATP showed a similar concentration-dependence in their kinetics. 5. Inward currents evoked by ATP, 2-meSATP and alpha, beta-meATP (300 nM) were abolished by the P2-purinoceptor antagonist, suramin (100 microM). 6. UTP (10 microM) evoked similar transient inward currents, which were sensitive to suramin (100 microM). ATP (10 microM), applied 2 min beforehand, reduced the response to UTP (10 microM) by 80 +/- 10%. 7. This study shows that ATP, 2-meSATP and alpha, beta-meATP act via a suramin-sensitive P2x-purinoceptor to evoke rapid, transient inward currents in dissociated neurones of rat dorsal root ganglia. The pyrimidine nucleotide, UTP, was also active. It is likely that the agonists were acting at the P2x3-subtype to produce these effects.

Adenosine Triphosphate↗
PubMed1996

Stimulation by the nucleotides, ATP and UTP of mitogen-activated protein kinase in EAhy 926 endothelial cells.

1. We have investigated the characteristics of activation of the 42kDa isoform of mitogen-activated protein (MAP) kinase in response to various nucleotides in the endothelial cell line EAhy 926. 2. Adenosine 5'-triphosphate (ATP) in the concentration range 0.1-100 microM stimulated the rapid and transient tyrosine phosphorylation and activation of the 42 kDa isoform of MAP kinase in EAhy 926 endothelial cells which peaked at 2 min and returned to basal values by 60 min. ATP also stimulated a similar response in primary cultured bovine aortic endothelial cells. 3. Uridine 5' triphosphate (UTP) also stimulated the 42 kDa isoform of MAP kinase with similar potency to ATP (EC50 values 5.1 +/- 0.2 microM for UTP; 2.9 +/- 0.8 microM for ATP), whilst the selective P2Y-purinoceptor agonist, 2-methylthioATP (2-meSATP) was without effect up to concentrations of 100 microM. In bovine aortic endothelial cells however, UTP and 2-meSATP both stimulated MAP kinase. 4. Pretreatment of cells for 24 h with 12-O tetradecanoyl phorbol 13-acetate resulted in the loss of the alpha and epsilon isoforms of protein kinase C (PKC) and virtual abolition of nucleotide-stimulated MAP kinase activity (> 90% inhibition). 5. Preincubation for 30 min with the PKC inhibitor, Ro-31 8220 (10 microM) reduced MAP-kinase activation at 2 min but potentiated the response at 60 min. 6. Removal of extracellular calcium in the presence of EGTA reduced the MAP kinase activation in response to UTP by approximately 30-50%. 7. Pretreatment with pertussis toxin (18 h, 50 ng ml-1) did not significantly affect the UTP-mediated activation of pp42 MAP kinase. 8. These results show that in the EAhy 926 endothelial cell line, nucleotides stimulate activation of MAP kinase in a protein kinase C-dependent manner through interaction with a P2U-purinoceptor.

Adenosine Triphosphate↗
PubMed1996

Expression from the nifB promoter of Azotobacter vinelandii can be activated by NifA, VnfA, or AnfA transcriptional activators.

In Azotobacter vinelandii, nifB is required for the activity of all three nitrogenases. Expression of a nifB-lacZ fusion was examined to determine which regulatory gene products are important for nifB expression and how its transcription is regulated in response to metals. In all conditions, expression in A. vinelandii was eliminated by an rpoN mutation, confirming the absolute requirement for sigma N. In the wild type, nifB-lacZ expression was approximately twofold higher in cells grown with Mo than without. Expression was negligible in a nifA mutant grown with Mo but was much higher in Mo-free medium, suggesting that in these conditions, another sigma N-dependent activator was responsible for nifB expression, possibly VnfA, AnfA, or NtrC. Although expression of the nifB-lacZ fusion in A. vinelandii vnfA, anfA, and ntrC mutants was little different from that in the wild type, nifB transcription could be activated by NifA, VnfA, or a truncated form of AnfA in Escherichia coli. The two potential NifA binding sites centered at -87 and -129 bp upstream of the transcription start site each overlapped a VnfA recognition sequence, motifs also found in Azotobacter chroococcum in two exactly conserved regions. Deletion analysis showed that both regions are important for nifB expression. Activation of the full-length promoter by AnfA was impaired by overexpressing the DNA-binding domain of NifA, suggesting that binding of NifA and AnfA can be competitive.

Azotobacter vinelandii↗
PubMed1996

Roles of gall bladder emptying and intestinal transit in the pathogenesis of octreotide induced gall bladder stones.

BACKGROUND: Octreotide treatment of acromegalic patients increases the % deoxycholic acid conjugates and the cholesterol saturation of gall bladder bile, and induces gall stone formation. AIMS: To study the roles of gall bladder emptying and intestinal transit in these phenomena. METHODS AND PATIENTS: Gall bladder emptying and mouth to caecum transit was measured in (a) control subjects and acromegalic patients given saline or 50 micrograms of octreotide, and (b) acromegalic patients taking long term octreotide. In the second group, large bowel transit was also measured. RESULTS: A single dose of octreotide inhibited meal stimulated gall bladder emptying, the ejection fraction falling from mean (SEM) 66.0 (2.3)% to 7.0 (5.3)% in controls (p < 0.001); from 72.5 (2.1) to 16.6 (5.1)% in untreated acromegalic patients (p < 0.001), and to 30.4 (9.5)% in acromegalic patients taking long term octreotide (p < 0.001 v untreated acromegalic group). Octreotide prolonged mouth to caecum transit time, from 112 (15) min to 237 (13) min in controls (p < 0.001), from 170 (13) min to 282 (11) min in untreated acromegalic patients (p < 0.001), and to 247 (10) min in acromegalic patients taking long term octreotide (p < 0.001 v untreated acromegalic patients). The mean large bowel transit in octreotide untreated compared with treated acromegalic patients remained unchanged (40 (6) h v 47 (6) h). CONCLUSIONS: Prolongation of intestinal transit and impaired gall bladder emptying may contribute to lithogenic changes in bile composition and gall stone formation in patients receiving long term octreotide.

Acromegaly↗
PubMed1996

Telemedicine applications in an integrated mental health service based at a teaching hospital.

Psychiatric applications have predominated in Australian telemedicine in recent years. This paper describes the development of the first telemedicine system for an integrated mental health service based at a teaching hospital. Much effort was devoted to training and education for staff. Within about six weeks of the system being installed, over 80% of all clinical administrative staff, from all the mental health disciplines of the integrated service, had completed a formal training programme. Applications within the service included direct clinical work and the use of videoconferencing in preference to standard telephony over short distances. Applications external to the service, over distances of thousands of kilometres, included clinical supervision and teaching. Evaluation is continuing.

Community Mental Health Services↗
PubMed1995

Preservation of autoregulatory cerebral vasodilator responses to hypotension after inhibition of nitric oxide synthesis.

Effects of inhibition of nitric oxide (NO) synthesis on the cerebrovascular autoregulatory vasodilator response to hypotension were studied in conscious rats. Cerebral blood flow (CBF) was determined with [14C]iodoantipyrine in a saline-treated control group and in three groups following inhibition of NO synthase activity by twice daily intraperitoneal injections of 50 mg/kg of NG-nitro-L-arginine methyl ester (L-NAME) for four days. In the saline-control group (n = 8) and in the L-NAME-treated Group (a) (n = 8) CBF was determined while systemic mean arterial blood pressure (MABP) remained at its resting level (means +/- S.D., 128 +/- 6 and 151 +/- 11 mmHg, respectively). In the other groups CBF was determined after MABP was reduced by blood withdrawal to 118 +/- 9 and 88 +/- 8 mmHg in Groups (b) (n = 8) and (c) (n = 8), respectively. Despite the elevated MABP, global CBF was significantly lower in L-NAME-treated Group (a) than in the saline-controls (P < 0.005), indicating cerebral vasoconstriction resulting from inhibition of NO synthesis. Global CBF was not significantly reduced further in the two groups with hypotension. Local CBF in the hypotensive rats showed no significant reductions below values in L-NAME-treated control rats (Group (a)) in 31 of 32 brain structures; the only exception was in the auditory cortex of the severely hypotensive rats (Group (c)). The autoregulatory mechanism for cerebral vasodilatation to compensate for reduced arterial blood pressure is maintained following inhibition of NO synthesis.

Animals↗