Syndrome of inappropriate secretion of antidiuretic hormone associated with angiotensin-converting enzyme inhibitor therapy in the perioperative period

Introduction:

Angiotensin-converting enzyme (ACE) inhibitors are one of the most commonly used medications for hypertension. Rarely, ACE inhibitors have the potential to cause a syndrome of inappropriate secretion of antidiuretic hormone (SIADH).

Case presentation:

A 70-year-old woman with > 10 years ACE inhibitor therapy with normonatremia suddenly developed severe SIADH when she took a liquid diet in the uneventful perioperative period, with hemodynamic stability and no surgical complications. She promptly recovered from SIADH subsequent to discontinuing the ACE inhibitor therapy and changing her diet. Therefore, it was assumed that excess antidiuretic hormone secretion due to an ACE inhibitor and free water load from the liquid diet contributed to hyponatremia in our patient.

Conclusion:

Patients treated with an ACE inhibitor can latently experience inappropriate secretion of antidiuretic hormone, and rapidly develop severe hyponatremia together with additional factors affecting water or salt homeostasis regardless of the length of the administration duration. Clinicians should monitor serum sodium levels in such patients not only just after the initiation of ACE inhibitors but also upon the appearance of those factors.

Clinical features and varieties of non-motor fluctuations in Parkinson's disease: a Japanese multicenter study

OBJECTIVE

This multicenter cross-sectional study aimed to investigate the clinical features and varieties of non-motor fluctuation in Parkinson's disease (PD).

METHODS

To identify motor and non-motor fluctuation, we employed the wearing-off questionnaire of 19 symptoms (WOQ-19) in 464 PD patients. We compared the frequency of levodopa-related fluctuation as identified by the WOQ-19 with recognition by neurologists. We compared patients with both motor and non-motor fluctuations with those who only had motor fluctuations. Non-motor fluctuations were separated into psychiatric, autonomic, and sensory categories for further analysis.

RESULTS

The patients' average age was 70.8 ± 8.4 years (mean ± SD) and disease duration was 6.6 ± 5.0 years. The frequency of motor fluctuations was 69% and for non-motor fluctuation 40%. Fifty-three percent of patients with motor fluctuations also had non-motor fluctuations, whereas 93% of patients with non-motor fluctuations also had motor fluctuations. The WOQ-19 showed a sensitivity of 82% but a specificity of only 40%. The patients with both non-motor and motor fluctuations exhibited more severe motor symptoms, more non-motor symptoms and higher levodopa daily doses (p < 0.05). Patients had significantly higher fluctuation rates if they had psychiatric (49%) and sensory (45%) symptoms than patients with autonomic symptoms (32%, p < 0.01). Forty-eight percent of patients with non-motor fluctuations exhibited more than one type of non-motor fluctuation.

CONCLUSION

Forty percent of PD patients presented with non-motor fluctuations, and almost half of these exhibited more than one type. Appropriate recognition of levodopa-related fluctuations, both motor and non-motor, can lead to treatment modifications in PD patients.

REM sleep behavior disorder in Japanese patients with Parkinson's disease: a multicenter study using the REM sleep behavior disorder screening questionnaire

REM sleep behavior disorder (RBD) is known to be observed more frequently in patients with an α-synucleinopathy such as Parkinson's disease (PD) than in the general population. The precise prevalence of RBD in Japanese PD patients is not known. Therefore, we investigated the prevalence and the clinical characteristics of patients with RBD in a large population of Japanese patients with PD. We investigated various clinical features and employed the Japanese version of the RBD screening questionnaire on 469 non-demented Japanese PD patients in this multicenter study. Probable or possible RBD was detected in 146 patients (31.1%) and was significantly associated with longer PD duration, higher Hoehn and Yahr stage, higher Unified Parkinson's Disease Rating Scale part III subscale (7 items), more motor fluctuations, and a higher levodopa-equivalent daily dose (p < 0.01). As to the major autonomic dysfunctions, severe constipation was significantly more frequent in PD patients with RBD than in those without it (p < 0.01). The RBD symptoms of 53 patients (39.0%) preceded the onset of PD motor symptoms. The median interval from the onset of RBD symptoms to PD motor symptoms was 17.5 years, and 3 patients had intervals of over 50 years. This large-scale multicenter study revealed that RBD is a frequent non-motor symptom in Japanese patients with PD, which may precede the onset of motor symptoms. Moreover, RBD that increases with the duration and severity of PD may be associated with autonomic dysfunction.

Camptocormia in Japanese patients with Parkinson's disease: a multicenter study

OBJECTIVE

The aim of this work was to investigate the prevalence of camptocormia and the clinical characteristics of patients with camptocormia in a large population of PD patients.

BACKGROUND

Although camptocormia has been recognized as a prominent phenomenon in PD, the previous epidemiological reports were limited, especially in terms of sample size.

METHODS

We evaluated 531 PD patients (disease duration: 7.0 ± 5.5 years, mean ± standard deviation). We examined their clinical features and the prevalence of camptocormia.

RESULTS

Camptocormia was detected in 22 patients (4.1%) and found in patients who were older and had more severe motor symptoms and a higher levodopa (L-dopa) dose (P < 0.05), compared to the patients without camptocormia. Patients with camptocormia showed significantly higher frequencies of autonomic symptoms, such as constipation and urinary incontinence (P < 0.05).

CONCLUSIONS

Camptocormia is uncommon in PD and is associated with disease severity, higher L-dopa dose and higher frequencies of autonomic symptoms.

[Case of consciousness disturbance following a fever with spreading lesion over the bilateral splenia of the corpus callosum on MRI]

We report a 66-year-old man with spreading lesion over the bilateral splenia of the corpus callosum shown on MRI. On admission, unknown fever and myoclonus-like involuntary movement in the left forefinger and middle finger were observed. There were no remarkably abnormal data in the serum, the cerebrospinal fluid and electroencephalogram. However, T2-weighted MRI revealed the high signal spreading over the bilateral splenia of the corpus callosum, while enhanced effects were not observed by Gd contrast on T1-weighted MRI. Diffusion and FLAIR MRI also showed the high signals limited to the same part of the splenia bilaterally as on T2-weighted MRI, discriminating it from other lacunar lesions and old cerebral infarctions. Neurological features, which were considered to be directly associated with the fresh lesion, were impairment of verbal and visual memories. Near the time the therapies including high-dose steroid were given, the consciousness of the patient worsened rapidly on a day-to-day basis and disseminated intravascular coagulation syndrome (DIC) also occurred. By administering low-molecule heparin, consciousness disturbance and involuntary movements recovered completely. Following the improved symptoms, FLAIR MRI showed a reduced level of the signal seven months after the onset. A demyelinating disease over the bilateral splenia of the corpus callosum should be considered as the final diagnosis. Follow-up of the changes in this case is expected to provide a more accurate diagnosis.

[A case of cerebral putaminal hemorrhage complicating a brain abscess proved by craniotomy]

A 40-year-old man was admitted to our hospital because of consciousness disturbance, dysarthria and numbness in his right hand. Computed tomography of the head showed a cerebral hemorrhage of the left putamen. The patient was judged to have an indication of operation, and frontal craniotomy to evacuate hematoma was performed. During the operation, massive whitish pus flowed out at the time of surgery. Therefore, hemorrhage into a brain abscess was diagnosed. We reported this unique and interesting case whose brain abscess could not be differentiated from an ordinary hypertensive putaminal hemorrhage based on clinical findings and CT image. This diagnosis was not made until the patient was operated on through a craniotomy.

Obesity as a risk factor for cerebrovascular disease

Obesity is widely recognized as a risk factor for coronary artery disease, but opinion is divided regarding whether it is an independent risk factor for cerebrovascular disease; even now there is no common view. In this study, the review sought to focus on a prospective study, but since obesity and non-obesity basically cannot be randomly assigned, randomized controlled trials (RCT) are nonexistent. Accordingly, a cohort study (a method of clinical study in which the obesity group is actively followed up for comparison with the non-obesity group in regard to cerebrovascular disease) was mainly conducted. For reference, retrospective case-control studies are also shown. As a result, most epidemiological surveys on the relation between simple obesity and cerebrovascular disease denied any relation. That is, obesity alone, determined only on the basis of height and weight as shown by BMI (body mass index), etc., cannot be an independent risk factor for cerebrovascular disease; obesity can become a risk factor only when accompanied by hypertension, hyperlipidemia, impaired glucose tolerance, etc. Recently, however, most papers conclude that abdominal obesity is a risk factor for cerebral infarction, provided that there are no data confirming that obesity is a risk factor for hemorrhagic cerebrovascular disease (cerebral hemorrhage and subarachnoid hemorrhage).

[A young patient of acute encephalitis complicated with acyclovir encephalopathy without renal dysfunction]

A previously healthy 30-year-old woman was admitted to our hospital because of impaired consciousness after convulsion. A temporary diagnosis of herpes simplex encephalitis was made, and intravenous acyclovir (ACV) therapy (250 mg four times daily in normal saline over 2 hours) was started. Three days later, she became confused, and was having hallucinations, dysarthria and generalized painful seizures occurred without focal neurologic deficit. Whether the neuropsychiatric symptoms were related to herpes simplex encephalitis or acyclovir neurotoxity was initially unclear. The brain MRI and lumbar puncture findings were initially normal, but abnormal FLAIR lesions appeared later. ACV-associated encephalopathy was considered. ACV was discontinued, and she recovered from the neurological disorder within 24 hours. Although blood levels of acyclovir were not determined, it is unlikely that they were in a toxic range, in view of her normal renal function.

CD7+ and CD56+ myeloid/natural killer cell precursor acute leukemia treated with idarubicin and cytosine arabinoside

We describe a 69-year-old Japanese male with acute leukemia with a CD7+ and CD56+ immunophenotype presenting with multiple lymphadenopathy. He was treated with idarubicin and cytosine arabinoside. Although the leukemia showed partial response, the patient did not achieve complete remission. He died of sepsis due to severe neutropenia after the third course of chemotherapy. His autopsy revealed blast infiltration in the lymph nodes, liver, spleen and vertebral bone marrow. Recently, CD7+ and CD56+ myeloid/natural killer precursor acute leukemia has been associated with a poor prognosis. Our case illustrates that myeloid/natural killer cell precursor acute leukemia shows some response to intensive chemotherapy for acute myeloid leukemia, but such therapy is insufficient to effect a cure. To overcome the resistance of this disease to chemotherapy, further studies should explore other treatment strategies.

Distribution of brain oedema in the contralateral hemisphere after cerebral infarction: repeated MRI measurement in the rat

The appearance of local cerebral dysfunction at remote regions from the focus in the acute stage of stroke (diaschisis) is well known, but its mechanism has not been established. We have analysed serial MR images of the infarcted brain of rats to evaluate the distribution of oedema. Forty-seven Sprague-Dawley rats were anaesthetized with halothane, and the right middle cerebral artery (MCA) was permanently occluded via the intraluminal approach using a nylon 2-0 suture. At 3, 6, 9 and 24 hours after the occlusion, coronal T(2)-weighted MR images were taken and the signal intensity (SI) was computed at each region of the brain. After occlusion of the right MCA, SI increased diachronically up to 24 hours on the occluded side of the cortex (52.9+/-3.2 to 104.8+/-22.4) and striatum, which are within the perfusion territory of the MCA. SI increment was also observed at the hippocampus, alveus hippocampi and pyriform lobe, which are not within the territory of the MCA, and at some regions of the contralateral side (52.5+/-4.8 to 69.4+/-14.8 at the cortex). These changes were prominent in ischaemia-vulnerable portions, mild in the cortex, and minimal in the striatum. This contralateral side SI increment indicates remote oedema, which corresponds to diaschisis. We suggest that the mechanism of this remote contralateral oedema is the movement of extravasated protein from the lesion.

Modern Japanese medical history and the European influence

Before the first European visited Japan in 1549, traditional Chinese medicine was mainly employed in Japan. Francisco de Xavier, a missionary of the Society of Jesus, tried to promote the introduction of Christianity by providing a medical service for Japanese citizens. However, Japan implemented a national isolation policy in 1639 and cut off diplomatic relations with the rest of the world, except Holland and China. For over 200 years, until the American admiral Matthew Perry forced Japan to open its doors in 1853, Japan learned about western medicine only from doctors of the Dutch merchants' office or from Dutch medical books. After 1853, Western medicine was rapidly introduced into Japan, and great achievements by Japanese medical doctors soon followed, such as the serum therapy for tetanus, the discovery of the plague and dysentery bacilli, the invention of Salvarsan for the treatment of syphilis, and the demonstration of the neurosyphilis spirochete.

[A case of codon 232 mutation-induced Creutzfeldt-Jakob disease visualized by the MRI-FLAIR images with atypical clinical symptoms]

A 50-year-old man was admitted to our hospital because of disorientation and nocturnal restlessness. The patient presented chronically progressive dementia. No myoclonus or periodic synchronous discharge (PSD) was found over time, with abnormal evidence in MRI-FLAIR (fluid-attenuated inversion recovery) images alone. Brain biopsy and prion protein gene analysis led to the final diagnosis of Creutzfeldt-Jakob disease (CJD) induced by the point mutation at codon 232 (Met to Arg). To date the cases of M232R mutation-induced CJD have been reported to present clinical symptoms and pathological evidences similar to sporadic CJD cases, and differential diagnosis between the types has been believed to be difficult. Our case suggests that some types of CJD induced by point mutation at codon 232 cannot be easily inferred from clinical findings.

How to use cerebral vasodilators and metabolic activators

Cerebral vasodilators and metabolic activators (enhancers) for the treatment of cerebrovascular disorders (CVD) have been categorized and introduced into clinical practice according to their pharmacological actions and clinical indications. The main therapeutic goal of these drugs is to relieve residual subjective symptoms and neuropsychological dysfunction, which reduce the quality of life of patients in the chronic stage of stroke. Selection of the most suitable drug for the individual symptoms of each patient is an important therapeutic principle.

Experimental models and treatment trials for cerebral infarction

Recent progress in both experimental and clinical studies of cerebral infarction is outlined, and research on delayed neuronal death and ischemic penumbra is described. Development of animal models to study clinical pathophysiology is reviewed, and our focal cerebral ischemia model which has been used for many years is introduced. With elucidation of the pathophysiology of cerebral ischemia, various pharmaceutical agents have appeared recently in the clinical setting and our experimental trials on the treatment of cerebral ischemia are also introduced. From the clinical aspect, practical methods of treatment including antiplatelet therapy are explained. Cerebrovascular dementia and its prevention are also described.

Rapid changes in pial arterial diameter and cerebral blood flow caused by ipsilateral carotid artery occlusion in rats

We investigated rapid changes in pial arterial diameter and in cerebral blood flow (CBF) caused by transient ipsilateral common carotid artery occlusion (CCA-O) in anesthetized rats in order to elucidate how the cerebral circulation reacts to acute stem artery occlusion. In separate groups of rats, pial arterial diameter was recorded through a closed cranial window and CBF was recorded by laser-Doppler flowmetry. CCA-O was performed for 5 minutes under normotension and normocapnia (control) and under graded hypotension, hypercapnia and hypocapnia. In the control condition, pial arterial diameter increased rapidly, triggered by CCA-O. It took 12 +/- 3 s to reach the maximum of 204 +/- 42% of the value before CCA-O, and 60 +/- 24 s to become stable at 131 +/- 11%. CBF decreased rapidly to 66 +/- 11%, then increased reactively to 135 +/- 9%, and again decreased to 91 +/- 3%. The reactive increase in CBF caused by CCA-O decreased in parallel with the degree of hypotension, and also became barely detectable under hypercapnia. Our data suggest that active vascular dilation in the territory of the occluded artery is important for inducing collateral circulation.

Superacute phase blood pressure elevation may relate to massive hematoma in hypertensive putaminal hemorrhage

A restrospective clinical investigation has been performed to elucidate the relationship between hematoma size in putaminal hemorrhage and blood pressure (BP) changes during the immediate post-hemorrhagic phase in the emergency room (ER). Thirty-seven adult patients brought to the emergency department by ambulance within 6 hours after onset of symptoms with a confirmed diagnosis of acute putaminal hemorrhage on CT have been involved. Two BP measurements during the superacute phase in the ER have been studied: immediately after arrival at the ER (BP-I), and immediately prior to CT examination (BP-II). Patients have been divided into 6 categories: 1) those whose BP decreased with treatment (D+), 2) those whose BP decreased without treatment (D-), 3) those whose BP increased in spite of treatment (I+), 4) those whose BP increased without treatment (I-), 5) those whose BP remained unchanged in spite of treatment (U+), and 6) those whose BP remained unchanged without treatment (U-). Hematoma size has been compared among 5 categories (D+, D-, I-, U+, U-) using factorial ANOVA (analysis of variance). The hematoma sizes have been found to be (D+) 54 +/- 44 ml, (D-) 22 +/- 25 ml, (I-) 102 +/- 58 ml, (U+) 11 +/- 5 ml, (U-) 21 +/- 9 ml (mean +/- S.D.), respectively. (I-) has been significantly larger than any of the other categories (p < 0.001 - 0.05). Additional ANOVA has shown that BP-II in category (I-) was significantly higher than that of the other categories. Patients with putaminal hemorrhage whose BP was elevating during the superacute phase in the ER were shown to have massive hematomas.

Exclusion of the expansion of CAG/CTG repeats at thirteen loci on chromosome 12 as a candidate genetic mutation in scapuloperoneal spinal muscular atrophy with anticipation

Scapuloperoneal spinal muscular atrophy (SPSMA) is a neuromuscular disorder characterized by weakness in the distribution of shoulder girdle and peroneal muscles. We have previously described a large New England kindred with autosomal dominant SPSMA and have subsequently linked this family trait to 12q24.1-q24.31. In this family, disease expression becomes more severe and progressive in successive generations, suggesting genetic anticipation. Accordingly, we have investigated the thirteen known CAG/CTG repeat loci on chromosome 12 that could be tested by using the polymerase chain reaction as candidate genetic mutations in SPSMA. None of these loci is expanded.

Linkage of scapuloperoneal spinal muscular atrophy to chromosome 12q24.1-q24.31

Scapuloperoneal (SP) syndromes are heterogeneous neuromuscular disorders which are characterized by weakness in the distribution of shoulder girdle and peroneal muscles. SP syndromes can resemble facioscapulohumeral muscular dystrophy (FSH) due to scapular weakness or Charcot-Marie-Tooth disease (CMT) due to atrophy of peroneal muscles. Both neurogenic and myopathic SP syndromes have been described. Locus for the myopathic form of SP syndrome (scapuloperoneal muscular dystrophy, SPMD) has recently been assigned to chromosome 12q. We previously described a large New England kindred exhibiting an autosomal dominant neurogenic SP syndrome (scapuloperoneal spinal muscular atrophy, SPSMA). Disease expression was more severe and progressive in successive generations, which suggested genetic anticipation. We performed genetic linkage analysis of this family with microsatellite markers and excluded the loci for FSH, CMT, SPMD and SMA (spinal muscular atrophy) in our family. Linkage in our SPSMA family (lod score > 3) was established to seven microsatellite markers that map to chromosome 12q24.1-q24.31. The highest lod score with two-point linkage analysis was 6.67 (theta = 0.00) with marker D12S353. Multipoint analysis gave maximum lod scores of 7.38 between D12S354 and D12S79, and also 7.38 between D12S369 and NOS1 (neuronal nitric oxide synthase). The gene for SPSMA lies within the 19 cM interval between D12S338 and D12S366. This report establishes a locus for the neurogenic form of SP syndrome approximately 20 cM telomeric to the one described for the myopathic form of SP syndrome.

[A case of posttraumatic spinal pseudomeningocele which caused spinal cord compression 20 years after injury]

We reported an extremely rare case of posttraumatic spinal pseudomeningocele which caused spinal cord compression 20 years after getting injury, and demonstrated that sequelae of an injury may occur many years after the original wound. A 39-year-old man, who got left cervical root avulsion due to a traffic accident when he was 17 years old, began to complain of progressive muscle atrophy and weakness of left lower extremity 1 year ago. Myelography demonstrated pseudomeningocele at left C6-C8 level, and MRI and CT myelography revealed that the pseudomeningocele extends through the intervertebral foramen and compresses the spinal cord to the right side in the spinal canal. Bilateral functional compression of spinal cord dorsal and lateral column was also verified with SEP and MEP electrophysiologically.

Distribution and origins of cerebrovascular NADPH-diaphorase-containing nerve fibers in the rat

Neuronal NADPH-diaphorase has been proved to be nitric oxide synthase itself. In this study, we investigated distribution and origins of NADPH-diaphorase-containing nerve fibers in the cerebral vessels in the rat. Adult male Sprague-Dawley rats were divided into 4 groups. Nasociliary nerves were transected bilaterally in group 1. In group 2, intracranial branches of the sphenopalatine ganglion were transected bilaterally. In group 3, both of these structures were transected. The remaining animals were served as control (group 4). Two weeks after the above procedures, they were perfused with paraformaldehyde and glutaraldehyde. The pial arteries and superior cervical, trigeminal, internal carotid, otic and sphenopalatine ganglia were dissected. All specimens were processed for NADPH-diaphorase histochemistry. Numerous NADPH-diaphorase-containing nerve fibers with varicosities forming plexuses were observed in the circle of Willis and its branches. Relatively thick nerve bundles were noted in the anterior half of the circle of Willis. They are most abundant in the internal ethmoidal artery. Approximately 5% of such fibers in anterior half of the circle of Willis disappeared in group 1, 90% in group 2, and no fibers were seen to remain in group 3. NADPH-diaphorase reaction was positive in the neurons of sphenopalatine, otic trigeminal and internal carotid ganglia. Among these ganglia, the reaction was prominent in sphenopalatine, otic and internal carotid ganglia. In summary: (1) NADPH-diaphorase-containing nerve fibers distribute to the circle of Willis and its branches.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of sympathetic stimulation on cerebral circulation

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 significant increase in BrPCO2 were observed during sympathetic stimulation. These changes suggested that sympathetic stimulation slightly decreased cerebral blood flow. The present results do not rule out a significant role for sympathetic regulation of cerebral circulation. Sympathetic constriction of the extraparenchymal vessels might be compensated for by secondary dilation of the intraparenchymal vessels elicited by a chemical control (escape phenomenon).

A MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) mtDNA mutation that induces subacute dementia which mimicks Creutzfeldt-Jakob disease

A 50-year-old woman with subacute dementia and brain atrophy on CT showed periodic synchronous discharge (PSD) on electroencephalogram (EEG) and myoclonus. She was initially suspected of suffering from Creutzfeldt-Jakob disease (CJD), but dramatically recovered over 5 months. Based on further investigations, the final diagnosis was mitochondrial encephalomyopathy with an A-to-G substitution at nucleotide position 3243 in mitochondrial DNA (mtDNA), commonly seen in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). This case suggests that patients suspected of suffering from CJD should be evaluated for mitochondrial encephalomyopathy.

Cerebral ischemia-induced amplification phenomenon of somatosensory evoked potentials in cats

We elucidate the amplification phenomenon of median nerve somatosensory evoked potentials (SEPs) induced in cats by cerebral ischemia and also analyse the relationship between such amplification and cerebral blood flow (CBF). Transient focal cerebral ischemia was carried out by inducing only middle cerebral artery occlusion or jointly with bilateral common carotid artery occlusion. Various SEP alteration patterns were observed with CBF changes; with our overall results suggesting for the first time that the SEP amplification phenomenon occurs only under relatively mild cerebral ischemia.

Mechanisms of CBF augmentation during hypoxia in cats: probable participation of prostacyclin, nitric oxide and adenosine

To elucidate the mechanisms of CBF augmentation during hypoxemic hypoxia, we applied continuous monitoring of CBF and metabolism to examine the participation of prostacyclin, nitric oxide (NO), and/or adenosine in these mechanisms. Cats (n = 32) were anesthetized and ventilated artificially. Cerebrovascular reactivity to hypoxia was assessed by changes in CBF, brain tissue oxygen and carbon dioxide tensions, and mean arterial blood pressure (delta CBF, delta BrPO2, delta BrPCO2, and delta MABP) during a 3-min inhalation of 10% O2 + 90% N2 before and after the intracarotid administration of (1) indomethacin (1 mg/kg, a cyclooxygenase inhibitor, n = 11), (2) L-NG-monomethyl-arginine (LNMMA, 1 mumol/kg/min, an inhibitor of nitric oxide synthesis, n = 11), and (3) caffeine (20 mg/kg, an adenosine antagonist, n = 10). BrPO2 decreased significantly in all groups during the produced hypoxemic hypoxia. CBF significantly increased in this state before the administration of indomethacin, LNMMA, or caffeine, whereas it contrastively did not significantly increase after the administration of indomethacin or caffeine. In addition, CBF significantly decreased under hypoxia during the administration of LNMMA. Taken together, these results suggest that prostacyclin (PGI2), nitric oxide (NO), and adenosine may jointly participate in CBF augmentation during hypoxia.

Effect of sympathetic nervous system stimulation on cerebrovascular CO2 responsiveness

Cerebrovascular CO2 responsiveness, following noradrenaline (NA) infusion, was studied in the cat by continuous measurement of cerebral tissue oxygen tension (BrPO2), carbon dioxide tension (BrPCO2), pH (BrpH), and blood pressure (BP). Intravenous infusion of NA (1 microgram/kg/min) was done to stimulate the adrenergic nervous system. Inhalation of 5% CO2+air was performed for 3 minutes before, during, and after NA infusion. Cerebrovascular CO2 responsiveness was estimated from changes in BrPO2, BrPCO2, and BrpH. CO2 inhalation increased BrPO2, BrPCO2, and BP, but decreased BrpH, in the respective 3 stages. delta BrPO2 decreased significantly during NA infusion, but recovered after cessation of NA. NA infusion caused a decrease in CO2 responsiveness. This suggests that sympathetic hyperactivity can modify cerebrovascular CO2 responsiveness.

Alpha-adrenergic blockade with phenoxybenzamine enhances cerebrovascular CO2 reactivity

The influence of sympathetic nervous activity on cerebral circulation and cerebrovascular CO2 reactivity was investigated by an alpha-adrenergic blockade with phenoxybenzamine (PBZ). Cerebral oxygen and carbon dioxide tension (BrPo2, BrPco2) and arterial blood pressure were continuously recorded before, during and after intracarotid infusion of 5 mg/kg of PBZ. The effects of 5% CO2 inhalation were measured before and after the infusion of PBZ. Following the intracarotid infusion of PBZ, BrPo2 and BrPco2 did not change significantly. After the alpha-adrenergic blockade the degree of the increase in BrPo2 during 5% CO2 inhalation was significantly enhanced. The increase in the cerebrovascular CO2 reactivity produced by low dose PBZ suggests that the sympathetic nervous system modifies cerebrovascular CO2 reactivity.

Effect of clonidine on the cerebrovascular system in cats

The effects of clonidine, a potent alpha 2 adrenergic agonist and an imidazole/imidazoline receptor agonist, were examined in the cat cerebrovascular system, measuring cerebral oxygen and carbon dioxide tension (BrPo2, BrPco2) and arterial blood pressure. Intracarotid injection of clonidine (2 micrograms/kg) produced a gradual decrease in systemic blood pressure without initial hypertension, while BrPo2 decreased slightly but significantly. Before and after intracarotid administration of clonidine, cerebrovascular reactivity to carbon dioxide was estimated by changes in BrPo2 and BrPco2 during and after 3 min inhalation of 5% CO2. Clonidine significantly enhanced cerebrovascular reactivity to carbon dioxide. The data suggest that the alpha 2-adrenoceptor and/or imidazoline receptor play an important role in the regulation of cerebral circulation.

Cerebrovascular NADPH diaphorase-containing nerve fibers in the rat

Recently, neuronal nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase has been elucidated to be the nitric oxide synthase (NOS) per se. In order to examine the existence and distribution of cerebrovascular nerve fibers containing these substances, NADPH-diaphorase histochemistry was applied to the cerebral blood vessels and the cranial ganglia known to innervate the cerebral vessels in the rat. Numerous nerve fibers with varicosities forming plexuses were observed in the circle of Willis and its branches. In addition, thick nerve bundles were seen to run along the wall of the internal ethmoidal artery. NADPH-diaphorase reaction was prominent in neurons of the sphenopalatine, otic and internal carotid ganglia. This study demonstrated, for the first time, the NADPH-diaphorase-containing nerve fibers in the cerebral vessels and ganglion cells in the parasympathetic and sensory ganglia known to innervate the cerebral vessels.

Changes of pial vessel diameter and CO2 reactivity during insulin-induced hypoglycemia and in the recovery period following glucose administration

The present study examined the changes of cerebrovascular CO2 reactivity during insulin-induced hypoglycemia and in the recovery period following glucose administration in cats. The diameters of pial vessels were continuously measured using the vidicon camera system. Hypoglycemia was induced by intraperitoneal injection of Actrapid insulin (100 IU/kg). Cerebrovascular CO2 reactivity was estimated by the changes of pial vessel diameters during 3 min inhalation of 5% CO2 in air at each stage of glucose level. CO2 reactivity was impaired in the hypoglycemic stage and this impairment was further enhanced in the early recovery stage. In the late recovery stage, CO2 reactivity was restored particularly in the small arteries which were less innervated by autonomic nerves. These results suggest that the sympathetic activity plays an important role in the impairment of cerebrovascular CO2 reactivity during hypoglycemia.

Role of cyclooxygenase system in cerebrovascular responsiveness: different effects of indomethacin on CO2 responsiveness and dilatation by Ca(2+)-channel blocker

To investigate roles of prostaglandins in the regulation of cerebral blood flow, we compared effects of indomethacin, a cyclooxygenase inhibitor, on the cerebrovascular CO2 responsiveness with those on the cerebrovascular dilatory action of diltiazem, a Ca(2+)-channel blocker. Fifteen adult cats were used. The cerebral tissue oxygen tension, carbon dioxide tension, pH and blood pressure were measured continuously. Indomethacin (1 mg/kg) was infused into the carotid artery. In 8 cats, 3 min inhalation of 5% CO2 in air was performed before and after the indomethacin infusion. In 7 cats, diltiazem (100 micrograms/kg) was infused into the carotid artery for 3 min before and after the indomethacin infusion. The cerebrovascular CO2 responsiveness was significantly decreased (p < 0.05) after the administration of indomethacin. On the other hand, the cerebrovascular dilatation induced by the Ca(2+)-channel blocker was significantly increased (p < 0.05) after the administration of indomethacin. It is concluded that the products of cyclooxygenase system are involved in the cerebrovascular responsiveness both to CO2 and to Ca(2+)-channel blocker, but action mechanisms of prostaglandins may be different, that is, prostaglandians may enhanced cerebrovascular responsiveness to CO2 but diminish it to Ca(2+)-channel blocker.

Role of the sympathetic system in impairment of the cerebrovascular CO2 responsiveness during moderate hypoglycemia

We examined the mechanism of impairment of the cerebrovascular CO2 responsiveness in moderate hypoglycemia. Twelve fasted cats were used. The brain-PO2, brain-PCO2 and brain-pH were measured continuously with electrodes placed on the brain surface. Hypoglycemia was induced with insulin. Intravenous injection of hexamethonium (a sympathetic ganglion blocker, C6; 0.1 mg/kg) was performed at the following stages: Control, hypoglycemia and recovery. Before and after the C6 administration, 5% CO2 in air was inhaled for 3 min at the respective stages. The CO2 responsiveness (cerebrovascular dilatory response to increased PaCO2) at the control stage was not altered after the ganglionic blockade. At the hypoglycemic stage, the increase in BrPO2 by CO2 inhalation was significantly less than that at the control stage. This reduction of delta BrPO2 was significantly improved after the administration of C6. At the recovery stage, the CO2 responsiveness before and after the administration of C6 was not significantly different. An impaired CO2 responsiveness in the hypoglycemic state was improved by sympathetic ganglion blockade with C6 which did not alter the reactivity during normoglycemia. It is suggested that the sympathetic activity plays an important role in impairment of the cerebrovascular CO2 responsiveness during moderate hypoglycemia.

Effects of locus ceruleus lesions on the pericapillary nerve terminals in the feline brain

The effects of bilateral locus ceruleus (LC) lesions on the pericapillary nerve terminals were investigated in the feline brain parenchyma using electron microscopy. LC lesions were induced stereotaxically and the animals were sacrificed after intravenous administration of 5-hydroxydopamine (5-OHDA). The diameter and number of dense-cored vesicles (DCVs) and clear vesicles (CVs) in the pericapillary nerve terminals were measured. The number of DCVs in the nerve terminal was significantly decreased by bilateral LC lesions. The diameters of the DCVs and CVs decreased significantly as compared with those in the non-operated control group. These data suggest that the LC is closely related to the pericapillary nerve terminals in the brain parenchyma and that not only nerve terminals with DCVs but also those with CVs are affected by LC lesions.

Effects of mergocriptine on cerebral circulation and metabolism in cats

Mergocriptine (CBM 36-733, CAS 81968-16-3) is an ergot alkaloid derivative and a dopaminergic agonist. Effects of mergocriptine on cerebral circulation and metabolism were examined by monitoring cerebral tissue oxygen and carbon dioxide tension (BrPO2, BrPCO2), cerebral blood flow (CBF) and blood pressure (BP) in 10 cats. Mergocriptine (10 micrograms/kg) infused into the carotid artery produced a significant increase in CBF during the administration followed by a decrease in BrPO2 in parallel with a significant decrease in BP.

Controlled ultraviolet irradiation generates endothelial damage without affecting the nerve terminals of the cerebral artery in cats

The vesicles of adventitial autonomic nerve terminals were examined quantitatively under an electron microscope in controlled ultraviolet ray (UV)-irradiated cerebral vessels. Five cats whose basilar arteries were irradiated with UV (UV group) and 5 cats whose basilar arteries were irradiated with visible rays (control group) were compared. Endothelial vacuolation was observed only in the UV group. There was no statistically significant difference in the diameters of the dense-cored vesicles, related to noradrenaline, and clear vesicles, related to acetylcholine, between the two groups. It is concluded that controlled UV irradiation which generates endothelial damage does not affect the vascular adventitia ultrastructurally.

Moderate hypoglycemia induces ultrastructural changes in perivascular nerve terminals of cat cerebral arteries

A quantitative morphological analysis of the perivascular nerve terminals of cerebral arteries during moderate hypoglycemia was performed. 5-Hydroxydopamine (5-OHDA) was applied to discriminate dense-cored vesicles, related to noradrenaline, and clear vesicles, related to acetylcholine, under the electron microscope. Five hypoglycemic and 5 normoglycemic cats, all receiving 5-OHDA, were compared. In both the middle cerebral artery and vertebral artery, the dense-cored vesicles were significantly smaller and clear vesicles were significantly larger in hypoglycemia than in normoglycemia. These morphological changes in the vesicles may indicate hyperactivity of the sympathetic system and hypoactivity of the parasympathetic system of the cerebral vessels during hypoglycemia.

Effects of 3-isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine on cerebral circulation and metabolism in cats

Effects of 3-isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine (KC-404) on cerebral circulation and metabolism were examined measuring cerebral oxygen and carbon dioxide tension (BrPO2, BrPCO2) and mean arterial blood pressure (MABP) in cats. KC-404 (100 micrograms/kg) infused into the carotid artery produced no significant changes in BrPO2, BrPCO2 and MABP. 300 micrograms/kg of KC-404 infused into the femoral vein produced significant decrease in MABP, whereas BrPO2 remained constant. It is suggested that a large dose of KC-404 causes preferential cerebral vasodilation and maintenance of constant blood flow despite marked reduction in MABP.

Effects of nilvadipine on cerebral circulation and metabolism in cats

Effects of nilvadipine (FK 235) on cerebral circulation and metabolism were examined measuring cerebral oxygen and carbon dioxide tension (BrPO2, BrPCO2), pH (BrpH) and mean arterial blood pressure (MABP) in cats. Nilvadipine (10 micrograms/kg) infused into the carotid artery produced a remarkable and long-lasting decrease in systemic blood pressure, whereas BrPO2 and BrPCO2 increased significantly. The present study suggests that in addition to the improvement of the cerebral circulation, nilvadipine may augment cerebral metabolism.

Effects of 2-nitratopropyl 3-nitratopropyl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate on cerebral circulation and metabolism in cats

Effects of CD-349 (2-nitratopropyl 3-nitratopropyl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate) on cerebral circulation and metabolism were examined measuring cerebral oxygen and carbon dioxide tension (BrPO2, BrPCO2), pH (BrpH) and mean arterial blood pressure (MABP) in cats. CD-349 of 10 micrograms/kg infused into the carotid artery produced a remarkable and long-lasting decrease in systemic blood pressure, whereas BrPO2, BrPCO2 and BrpH did not change significantly. The previous studies have already demonstrated that CD-349 increases cerebral blood flow (CBF). In addition to the improvement of the cerebral circulation, the present study suggests that C-349 may augment cerebral metabolism.