Calcitonin gene-related peptide (CGRP) induces more potent vasorelaxation in the resistance portion than in the conduit portion of mesenteric arteries in humans

Although physiological processes related to vascular function differ greatly between resistance arteries and conduit arteries, it is not known whether the effects of calcitonin gene-related peptide (CGRP), a vasodilator neuropeptide, on these arteries differ in humans. In the present study, the conduit portion and the resistance portion of isolated human mesenteric arteries were suspended in a Krebs-Ringer solution. CGRP produced vasorelaxations in both portions. The EC50 values were very low both in the resistance portion (2.4 x 10(-9) M, n = 7) and in the conduit portion (2.2 x 10(-9) M, n = 7). The maximum response to CGRP in the resistance portion was significantly greater than that in the conduit portion (94.6 +/- 4.0% vs. 64.1 +/- 2.6% relaxation of methoxamine-induced precontraction, both n = 7, p < 0.01). These data suggest that CGRP is one of the most potent endogenous vasodilators in both the resistance portion and the conduit portion of the human mesenteric arteries, and that CGRP induces more potent vasorelaxation in the resistance portion than in the conduit portion of these arteries.

Oxytocin is hydrolyzed by an enzyme in human placenta that is identical to the oxytocinase of pregnancy serum

The hydrolysis of oxytocin (OT) by human placental subcellular fractions and pregnant sera was studied in the presence of bestatin, a potent inhibitor of aminopeptidases, and the antibody against pregnant serum oxyotocinase (P-LAP)(EC 3.4 11.3) by measuring liberated amino acids by high performance liquid chromatography (HPLC). Our immunotitration study and the effect of bastatin on the oxytocin-degrading protease showed that the initiating and responsible protease in oxyotocin degradation in human placenta and pregnant serum is P-LAP.

Carotid-cavernous sinus fistula and aneurysmal rupture associated with fibromuscular dysplasia. A case report

A patient with carotid-cavernous sinus fistula associated with fibromuscular dysplasia, who died from rupture of an associated splenic aneurysm despite successful treatment of the CCF, is reported. When multivessel involvement with aneurysmal dilatation is observed in patients with fibromuscular dysplasia, the possibility of aneurysm ruptures in any of the arteries should be considered.

Cooperative clinical trial of photodynamic therapy with photofrin II and excimer dye laser for early gastric cancer

BACKGROUND AND OBJECTIVE

Photodynamic therapy (PDT) is a recently developed endoscopic method for treating malignant tumors. For obtaining more photodynamic action with less thermal effect, we employed as the excitation light source for PDT an excimer dye laser, which is a pulsed laser with extremely high peak power, instead of an argon dye laser, which is a continuous wave laser and has been used conventionally.

STUDY DESIGN/MATERIALS AND METHODS

The effect of PDT using Photofrin II and the excimer dye laser was evaluated in 27 patients with early gastric cancer.

RESULTS

Complete responses (CR) were obtained in 88% of 24 assessable patients and the response rate was 100%. CR was observed in all cases of lesions of superficial depressed type without ulceration and/or with tumor diameter less than 2 cm. Regarding toxicity, mild cutaneous reaction and photosensitivity were seen and lasted several weeks. There were no serious abnormalities in laboratory tests.

CONCLUSION

We conclude that PDT is a promising modality for early gastric cancer.

[Genetic analysis of facioscapulohumeral muscular dystrophy (FSHD)]

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant muscular disorder which is characterized by progressive weakness and atrophy of the facial, shoulder-girdle and upper arm muscles, and occasional subsequent pelvic-girdle and lower limb involvement. The gene responsible for FSHD has been localized to chromosome 4q35-qter, although a few 4q-unlinked families are known. To examine FSHD-associated DNA rearrangements in the Japanese population, we performed Southern blot analysis of the genomic DNA, using the p13E-11 and pFR-1 probes. Most of the Japanese FSHD patients (> 95%) had specific smaller (< 28 kb) EcoRI fragments which cosegregated with the disease. Restriction enzyme maps of the polymorphic EcoRI fragment detected by the probes have revealed that the disease occurs due to a deletion of the integral numbers of the 3.3kb KpnI tandemly repeated fragments (D4Z4) which contain homeobox-like sequences. Indeed, we cloned and characterized the FSHD-associated EcoRI fragments (the shortest fragment identified to date: 10kb) from two severely affected patients (unrelated). The 10kb fragment were identical and contained only one 3.3kb KpnI repeat unit. Although we still do not know whether truncation deletion of the D4Z4 region could produce FSHD directly or indirectly (position effect), we now beginning to understand FSHD. In the next step, FSHD gene products (mRNA and protein) responsible for the disease should be investigated.

Localization of mRNA for phosphatidylinositol 3-kinase in brain of developing and mature rats

In the adult brain, the gene expression for phosphatidylinositol 3-kinase was weak in almost all neurons with relatively high levels in the olfactory bulb, hippocampus, and cerebellum. On the embryonic days high levels of the gene expression were found throughout the entire neuraxis, then decreased gradually to adult levels during postnatal development. The present finding suggests that phosphatidylinositol 3-kinase may contribute not only to neurogenesis but also to some important physiological roles in differentiating and mature neurons.

What is the difference of bone growth in SHR and SD rats?

1. Both sexes of spontaneously hypertensive rats (SHR) and Sprague-Dawley (SD) rats were used in this study. 2. At 6, 12, 18, 24, 30, 36, 42, 48, 54 and 60 weeks old, tibia length (L), volume (V), dry weight (DW), bone mineral density (BMD) in tibia and serum biochemical parameters (Ca2+, Ca, iP, ALP, TRAP) were measured. 3. At the 18 and 48 weeks old, bone morphometry was performed (mineral apposition rate, trabecular bone volume and trabecular thickness). Serum PTH and osteocalcin level were determined in 18 week old rats. 4. The time course change of DW, L and V were almost the same as the trends of bodyweight in each group, namely, male SD had the highest value, female SD and male SHR showed the same value and the lowest figures were obtained in female SHR. 5. BMD of the middle area showed almost the same trends with the time course change of bodyweight. On the other hand, both sexes of SHR had lower BMD than that of SD in the proximal area. 6. Serum biochemical parameters showed the same trends in both sexes of SD and SHR except for ALP (a marker of bone formation) which was higher in male than in female rats. 7. Mineral apposition rate, trabecular bone volume and trabecular thickness were not different between the same sex of SD and SHR. 8. These findings suggest that trabecular bone in SHR had a lower mineral status than that of SD rats not only in the adult but also in the young. This alteration may due to the abnormal mineralization mechanisms.

Initiating and responsible enzyme of arginine vasopressin degradation in human placenta and pregnancy serum

The hydrolysis of arginine vasopressin (AVP) by human placental subcellular fractions and pregnancy sera was studied in the presence of selective inhibitors and the antibody against pregnancy serum oxytocinase (P-LAP) (EC 3.4.11.3) by measuring liberated amino acids by high-performance liquid chromatography (HPLC). AVP degradation by placental subcellular fractions and pregnancy sera was inhibited by bestatin. The IC50 values of bestatin on AVP degradation by placental subcellular fractions and pregnancy sera were similar to that of this inhibitor on the P-LAP measured by L-Leu-p-nitroamnilide as a substrate (LAP activity), which we reported previously. Our immunotitration study clearly showed that the initiating and responsible protease in AVP degradation in human placenta and pregnancy serum is P-LAP. Since N-benzylcarbonyl-valyl-prolinal (Z-Val-prolinal), a selective inhibitor of post-proline endopeptidase, and phosphoramidon, a putative endopeptidase-24.11 inhibitor, could not significantly influence the degradation of AVP by placental microsomal fractions. Neither enzyme seems to be actively involved in AVP degradation.

[Removal of infected pacemaker leads in the elderly under extracorporeal circulation: two case reports and review of Japanese literature]

Two elder cases in whom infected pacemaker leads were removed under extracorporeal circulation (ECC) are reported. The leads could not be with drawn without direct sharp dissection under ECC because they had become firmly encased with fibrous tissue within the right ventricle. Postoperative courses were uneventful and neither of these patients has experienced recurrent infection to date. Removal with ECC seems to be a safe and effective procedure even in the elderly, provided that cardiac function is good.

Effect of the potassium channel opener YM934 on the contractile response to electrical field stimulation in pig detrusor smooth muscle

PURPOSE

The effect of a potassium channel opener, YM934, on the contractile response to excitatory neurotransmitters was investigated in isolated pig detrusor smooth muscle.

MATERIALS AND METHODS

Electrical field stimulation (EFS; 5 second trains, 50 V, 0.8 msec. duration), alpha, beta-MeATP (3 x 10(-7) to 10(-5) M.) or carbachol (3 x 10(-8) to 10(-6) M.) produced a contractile response in isolated pig detrusor smooth muscle. The effect of YM934 on the contractile responses was evaluated in comparison with the antagonism of the putative cotransmitters, acetylcholine and ATP.

RESULTS

A tetrodotoxin-sensitive, frequency-dependent contractile response to electrical field stimulation was obtained. Atropine (3 x 10(-8) M.) significantly inhibited the contractile response at high frequencies, whereas alpha, beta-MeATP (5 x 10(-6) M.) (desensitizer of P2X-purinoceptors) significantly inhibited the response at low frequencies. YM934 (10(-8) to 10(-7) M.) dose-dependently inhibited the nerve-mediated contractile responses to all frequencies but preferentially at low frequencies, by analogy with alpha, beta-MeATP. A combination of YM934 (3 x 10(-8) M.) and atropine (3 x 10(-8) M.) reduced the response at all frequencies to between 10 and 20% of control, an effect similar to that obtained with alpha, beta-MeATP (5 x 10(-6) M.) and atropine (3 x 10(-8) M.). In addition, YM934 (3 x 10(-8) M.) markedly inhibited the contractile response induced by exogenously applied alpha, beta-MeATP (3 x 10(-7) to 10(-5) M.) but only slightly inhibited the contractile response induced by exogenously applied carbachol (3 x 10(-8) to 10(-6) M.).

CONCLUSION

These results suggest that YM934 may hyperpolarize the membrane of pig detrusor smooth muscle through the opening of ATP-sensitive potassium channels and, as a result, may functionally inhibit the contractile response to purinergic nerve stimulation that elicits the membrane depolarization.

HTLV-I associated uveitis in central Japan

AIMS/BACKGROUND

Recently HTLV-I has been shown to cause a kind of endogenous uveitis in south west Japan, where HTLV-I infection is highly endemic. To investigate further the association of HTLV-I infection with the incidence of this uveitis, HTLV-I seroprevalence in central Japan, where HTLV-I infection is not endemic, was studied.

METHODS

HTLV-I seroprevalence was investigated in 1579 patients with various ocular diseases and 1251 normal volunteers as a younger control group. Then HTLV-I seroprevalence was compared in each group.

RESULTS

Of 1579 patients with various ocular diseases, 38 (2.41%) were seropositive. There was a statistically significant difference in HTLV-I seroprevalence between the undefined uveitis group and non-uveitic ocular diseases group (p < 0.05, Yates's correction). However, the seroprevalence in younger patients with undefined uveitis did not differ significantly from that in other groups. As regards the incidence of this type of uveitis, six of 12 (50%) seropositive patients, who were born in south west Japan and had lived in this area for 35 years, developed this undefined uveitis whereas only two of 26 (7.69%) seropositive patients in the other areas in Japan developed this uveitis. The difference was statistically significant (p < 0.05, Fisher's exact probability test).

CONCLUSION

These results suggest that the incidence of this type of endogenous uveitis could be greatly influenced by environmental or hereditary factors including HLA.

L-arginine and endogenous nitric oxide protect the gastric mucosa from endothelin-1-induced gastric ulcers in rats

We have reported that endothelin-1 induces gastric ulcer characterized by a potent long-lasting vasoconstriction of the regional microvasculature. Nitric oxide synthesized from L-arginine has been shown to regulated gastric mucosal blood flow, and inhibition of its synthesis has been shown to delay the healing of gastric ulcers. We examined the effect of exogenous L-arginine and the inhibition of nitric oxide synthesis on the development of endothelin-1-induced gastric ulcers. In rats anesthetized with urethane, a continuous intravenous infusion of L- or D-arginine (10 mg.kg-1.min-1) was followed, 15 min later, by a submucosal injection of endothelin-1 (200 pmol/kg) in the anterior wall of the gastric body. In another group, rats were intravenously pretreated with N omega-nitro-L-arginine-methyl ester (1-10 mg/kg), a nitric oxide synthesis inhibitor, and then injected with endothelin-1 (40 pmol/kg). Twenty-four h later, L-arginine, but not D-arginine, had significantly reduced the extent and the severity of the endothelin-1-induced ulcer (mucosal wall damage, 18.11 +/- 4.79% and 88.14 +/- 7.06%, respectively; mean +/- SD, P < 0.001), and the nitric oxide synthesis inhibitor (10 mg/kg) had increased the endothelin-1-induced mucosal damage (ulcer length, 3.8 +/- 1.2 mm and 1.1 +/- 0.2 mm, respectively, P < 0.01). Continuous gastric mucosal blood flow measurements showed that L-arginine antagonized the endothelin-1-induced vasoconstriction. L-arginine protected the gastric mucosa from the ulcerogenic action of endothelin-1 and antagonized its vasoconstrictive action. The inhibition of endogenous nitric oxide potentiated the ulcerogenic effect of endothelin-1 on rat gastric mucosa.

Detection of cilia-associated respiratory bacillus in experimentally and naturally infected mice and rats by the polymerase chain reaction

Cilia-associated respiratory (CAR) bacillus was detected by means of the reverse transcription (RT)-polymerase chain reaction (PCR), and the results were compared with those of indirect immunofluorescence test (IFAT) for the detection of the organism. In the experimental infections, 15 mice were in contact with mice previously inoculated with CAR bacillus. Three mice each were tested at days 3, 5, 7, 12 and 20 postexposure. On day 3 postexposure, CAR bacillus was detected in oral swab samples from all 3 mice by RT-PCR, but was not detected in any sampling sites from the mice by IFAT. Total numbers of positive samples from nasal, oral and tracheal swabs obtained through the test were 6/15, 14/15 and 8/15, respectively, by RT-PCR, and 2/15, 6/15 and 3/15, respectively by IFAT. For the detection of CAR bacillus in samples from 52 rats, 34 serum antibody negative rats by enzyme-linked immunosorbent assay were also negative by RT-PCR and IFAT except for one sample from the oral cavity, and all serum antibody positive rats were positive for the organism by RT-PCR but it could not be detected in five of them by IFAT. By means of RT-PCR, no differences in the positive rates depending on sampling sites were observed except in one rat. The RT-PCR was found to be a specific, highly sensitive and reliable procedure for detecting CAR bacillus in mice and rats. The oral cavity was the most suitable site for the diagnosis of the early stage of this infection by RT-PCR.

[The effect of subconjunctival injection of endothelin-1 on intraocular pressure in the rabbit]

Endothelin-1 (ET-1) is a potent vasoconstrictive peptide produced in part by vascular endothelial cells. In order to investigate its effects on the episcleral vascular system and intraocular pressure (IOP), we injected ET-1 (3, 10, 30, 100, 300, 1,000 pmol) into the subconjunctival space of rabbits and measured IOP with a manometer. Injection of a dose higher than 10 pmol caused a transient increase of IOP. Mean maximum elevation rate of IOP for each dose of ET-1 was 14.9 +/- 0.9%, (mean +/- standard error) 43.5% +/- 9.5%, 40.8 +/- 7.5%, 46.9 +/- 9.8%, and 84.1 +/- 22.6. Next, we injected 1,000 pmol into the subconjunctival space, and continuously measured IOP and ocular pulse pressure with a manometer. IOP increased rapidly after ET-1 injection. Maximal increase of IOP was observed at 22.7 +/- 9.2 min after ET-1 injection, and IOP decreased after the peak. The ocular pulse pressure increased with IOP elevation and decreased with the IOP reduction. We speculated that the transient elevation of IOP was caused by increase of aqueous outflow resistance, and the decrease of IOP was caused by decrease of aqueous outflow resistance and decrease of blood flow in the ciliary body and the choroid. This strongly suggests that subconjunctival injection of ET-1 could have a large effect on the episcleral vascular system, aqueous outflow, and blood flow in the ciliary body and the choroid.

Ultraviolet B irradiation increases endothelin-1 and endothelin receptor expression in cultured human keratinocytes

The effect of ultraviolet B (UVB) irradiation on endothelin-1 (ET-1) and ET receptor expression was examined using cultured normal human keratinocytes. Keratinocytes secreted ET-1 in the medium at a level of 2.1 pg/day/10(5) cells. UVB irradiation up to 10 mJ/cm2 increased ET-1 secretion 3-fold, and potentiated expression of mRNA for ET-1. Both ETA and ETB receptor mRNAs were detected in keratinocytes, and their expression was up-regulated by 5 mJ/cm2 UVB irradiation.

Effects of embryo density and co-culture of unfertilized oocytes on embryonic development of in-vitro fertilized mouse embryos

We have evaluated the effects of embryo density and the co-culture of unfertilized (degenerating) oocytes on the development of in-vitro fertilized (IVF) mouse embryos. In experiment 1, groups of one, five, 10 or 20 zygotes were cultured in 20 microliter drops of modified human tubal fluid (HTF) medium for 168 h at 38.7 degrees C in 5% CO2 and 95% air. As the embryo density increased, significantly (P < 0.05) higher rates of embryos reached hatched blastocyst stage. In addition, the time required for hatching after IVF was significantly (P < 0.05) shortened by the increase in embryo density. In experiment 2, 10 IVF zygotes were cultured with or without 10 unfertilized (degenerating) oocytes in 20 microliter drops of HTF medium. The rates of IVF embryos that developed to morula, blastocyst, expanded blastocyst and hatched blastocyst stages were decreased significantly (P < 0.01) by culturing embryos with unfertilized oocytes compared with culturing embryos alone. In experiment 3, groups of one or 10 IVF zygotes or 10 IVF zygotes plus 10 unfertilized oocytes were cultured in 20 microliter drops of HTF medium and the number of cells per blastocyst was examined at 120 h after IVF. Increasing embryo density resulted in a significant (P < 0.05) increase in the number of cells per blastocyst. In contrast, the cell number of IVF embryos that developed to blastocyst decreased significantly (P < 0.05) when they were cultured with unfertilized oocytes. The results suggest that in-vitro development of IVF mouse embryos is enhanced by increasing embryo density and is impaired by co-culture with unfertilized (degenerating) oocytes.

A severe muscular dystrophy patient with an internally deleted very short (110 kD) dystrophin: presence of the binding site for dystrophin-associated glycoprotein (DAG) may not be enough for physiological function of dystrophin

We report a 4-yr and 5-month-old boy with severe clinical features of an early-onset Duchenne muscular dystrophy, who had a very short (110 kDa) dystrophin at the sarcolemma. The patient had a large deletion (exons 2-44) of the dystrophin gene which was predicted to cause a reading frame shift. Sequence analysis of dystrophin mRNA in muscle revealed an alternatively spliced gene product from exons 1 to 51 that caused restoration of the reading frame, in addition to an mRNA corresponding to the DNA deletion. A consistent result was obtained by immunocytochemical analysis of muscle; i.e. positive staining for dystrophin at the sarcolemma using antibodies against the C-terminus, cysteine-rich region and last three of 24 repeat units of the central rod-domain, but not for the remaining antibodies for dystrophin that recognize the N-terminal and proximal rod-domains. Immunostaining for dystrophin-associated glycoproteins (DAGs: 43 and 50 K) and merosin were preserved. Utrophin staining was positive but fainter than other DMD muscles. These results suggest that an extremely short dystrophin lacking the entire actin-binding site in the N-terminus cannot function properly even if the protein possesses the putative DAG-binding cysteine-rich and the C-terminal domains, and still has an ability to associate with sarcolemmal membrane.

Spontaneous recurrence of methamphetamine psychosis: process and monoamine neurotransmitter function

We studied the process that causes a spontaneous recurrence of methamphetamine (MAP) psychosis, a phenomenon known as flashbacks, in 41 female flashbackers by a comparison of clinical characteristics between the 41 flashbackers and 87 non-flashbackers with previous MAP psychosis. We evaluated plasma levels of monoamine metabolites in 25 of the 41 flashbackers, 19 of the 87 non-flashbackers, 9 female patients with persistent MAP psychosis and 61 physically healthy female controls. All 41 flashbackers had experienced a significantly greater frequency of threatening events and threatening paranoid-hallucinatory states than the 87 non-flashbackers during previous MAP abuse. The triggering factor was a mild fear of other persons due to the evocation of frightening images, encoded through threatening experiences during previous MAP abuse. Norepinephrine (NE) levels were significantly associated with a history of flashbacks. Plasma 3-methoxy-4-hydroxyphenylglycol (MHPG) levels were significantly higher during flashbacks and during periods of normalcy in the flashbackers, and in the non-flashbackers, than MHPG levels in the user controls. NE levels in the patients with persistent MAP psychosis were also significantly higher than NE levels in the user controls. Elevated NE levels in the flashbackers were associated with disrupted NE, 5-HT and DA turnover. Thus, MAP-induced sensitization to frightening images may have caused the flashbacks due to aggravated noradrenergic hyperactivity.

[Seroprevalence of HTLV-I in various ocular diseases in central Japan]

Recently human T-cell lymphotropic virus type I (HTLV-I) has been shown to be responsible for a kind of uveitis in southwestern Japan, where HTLV-I infection is highly endemic. To investigate further the association of HTLV-I with various ocular diseases, we studied HTLV-I seroprevalence in 1,350 patients in central Japan, where HTLV-I infection is not endemic. Of 1,350 patients with various ocular diseases, 40 (2.96%) were seropositive for the retrovirus. There was no statistically significant difference in HTLV-I seroprevalence among various ocular diseases. Four of 9 (44.4%) seropositive cases from southwestern Japan developed HTLV-I associated uveitis (HAU), whereas only 2 of 26 (7.7%) seropositive cases from central Japan developed HAU. The difference was statistically significant (p < 0.05). This suggests that the incidence of HAU could be influenced by environmental or hereditary factors. On the other hand, 3 of 7 (42.9%) patients with episcleritis showed HTLV-I infection.

Prevalence of HTLV-I-associated uveitis in the Kanto Plain, Japan

BACKGROUND

Seroprevalence of antibody to human T-lymphotropic virus type I (HTLV-I) is high in the island of Kyushu, Japan. Reports on the etiological analysis of HTLV-I in patients with uveitis primarily document cases in this island. We studied the seroprevalence of HTLV-I at the Department of Ophthalmology in Yokohama City University Hospital and in Odawara Municipal Hospital, which are in the Kanto Plain on the island of Honshu, Japan.

METHODS

The subjects were 741 patients who visited the two hospitals. The presence of serum antibodies against HTLV-I was assessed using the method of particle agglutination.

RESULTS

Of 454 patients with nonuveitic ocular diseases, 9 (1.98%) were seropositive. Of 143 patients with definite diagnosis of uveitis, 1 (0.70%) was seropositive. Of 144 patients with non-specific uveitis (etiology undefined), 8 (5.56%) were seropositive. Thus, the prevalence of serum antibodies to HTLV-I was higher in patients with non-specific uveitis than in patients with specific uveitis or nonuveitic ocular diseases. Common ocular symptoms of 8 HTLV-I-infected patients with non-specific uveitis were compatible with the clinical features of uveitis described as HTLV-I-associated uveitis (HAU).

CONCLUSION

It is important to suspect HAU in patients with uveitis of unknown etiology, even outside known areas of prevalence.

Increase in choroidal blood flow in rabbits with endothelin-1 induced transient complete obstruction of retinal vessels

BACKGROUND

In a previous paper, we reported that retinal blood flow (RBF) ceased immediately after injection of 1 nmol endothelin-1 (ET-1) and no recovery of RBF was detected for at least 50 min. In this study, we confirmed the same duration of RBF cessation and measured choroidal blood flow (CBF) for 180 min.

METHODS

We measured CBF in a rabbit model of transient complete obstruction of retinal vessels induced by intravitreal injection of a high dose of ET-1, using the hydrogen clearance method. We also investigated the effects of intravitreal injection of ET-1 on intraocular pressure (IOP), blood pressure, pulse rate and blood gases.

RESULTS

CBF was significantly greater in the ET-1-injected eyes than in the control eyes 40-130 min after injection of ET-1 (P < 0.05). The maximal CBF ratio in the ET-1-injected eyes was 128 +/- 7.4% at 40 min. CBF decreased to the pre-injection level at 140 min after the injection of ET-1. There was no significant change in blood pressure, pulse rate and blood gases throughout this experiment, and there was no significant difference in IOP between ET-1-injected eyes and control eyes.

CONCLUSION

It seems likely that the increase in CBF resulted from some local mechanisms of control that compensated for the decrease in RBF induced by intravitreal injection of ET-1. This model may be useful for investigation of the regulatory system of intraocular circulation, including endothelin receptors.

The effect of bosentan, a new potent endothelin receptor antagonist, on the pathogenesis of cerebral vasospasm

Using the canine chronic cerebral vasospasm model, we studied the effects of a potent new nonpeptidic endothelin-1 (ET1) receptor antagonist, bosentan (Ro 47-0203, 4-tert-butyl-N-[6-(2-hydroxy-ethoxy)-5-(2-methoxy-phenoxy)-2,2'-bipyr imidin-4 - yl]-benzenesulfonamide). Endothelin (ET) receptors are composed of the ETA receptors and the ETB receptors; ET1 acts on both of these receptors. Although it has been previously thought that the ETA receptor mediates vasoconstriction, whereas the ETB receptor mediates vasodilation, recent evidence suggests that ETB receptor also contributes to vasoconstriction. Because bosentan is a mixed antagonist that acts on both receptors, its use might indicate whether or not ET is involved in the pathogenesis of cerebral vasospasm. In this study, beagle dogs received a double injection of autologous arterial blood into the cisterna magna at 2-day intervals (i.e., on Days 0 and 2). The diameter of the basilar artery (BA) was angiographically examined up to Day 7. A total of 24 dogs were randomly allocated to either the treatment group or the no-treatment group. Eight dogs were treated with 10 mg/kg bosentan by a one-dose injection into a central venous catheter. Bosentan was given twice a day starting immediately after the first subarachnoid hemorrhage for 6 days until Day 5. Sixteen dogs served as controls, with untreated subarachnoid hemorrhage. After the injection of bosetan, blood pressure decreased by about 25 mm Hg for a few minutes and then returned to normal. In the dogs treated with bosentan, the BA spasm on Day 7 was significantly ameliorated compared with the BA spasm in the untreated dogs.(ABSTRACT TRUNCATED AT 250 WORDS)