Cardiac-specific overexpression of angiotensin II AT2 receptor causes attenuated response to AT1 receptor-mediated pressor and chronotropic effects.

Angiotensin (Ang) II has two major receptor isoforms, AT1 and AT2. Currently, AT1 antagonists are undergoing clinical trials in patients with cardiovascular diseases. Treatment with AT1 antagonists causes elevation of plasma Ang II which selectively binds to AT2 and exerts as yet undefined effects. Cardiac AT2 level is low in adult hearts, whereas its distribution ratio is increased during cardiac remodeling and its action is enhanced by application of AT1 antagonists. Although in AT2 knock-out mice sensitivity to the pressor action of Ang II was increased, underlying mechanisms remain undefined. Here, we report the unexpected finding that cardiac-specific overexpression of the AT2 gene using alpha-myosin heavy chain promoter resulted in decreased sensitivity to AT1-mediated pressor and chronotropic actions. AT2 protein undetectable in the hearts of wild-type mice was overexpressed in atria and ventricles of the AT2 transgenic (TG) mice and the proportions of AT2 relative to AT1 were 41% in atria and 45% in ventricles. No obvious morphological change was observed in the myocardium and there was no significant difference in cardiac development or heart to body weight ratio between wild-type and TG mice. Infusion of Ang II to AT2 TG mice caused a significantly attenuated increase in blood pressure response and the change was completely blocked by pretreatment with AT2 antagonist. This decreased sensitivity to Ang II-induced pressor action was mainly due to the AT2-mediated strong negative chronotropic effect and exerted by circulating Ang II in a physiological range that did not stimulate catecholamine release. Isolated hearts of AT2 transgenic mice perfused using a Langendorff apparatus also showed decreased chronotropic responses to Ang II with no effects on left ventricular dp/dt max values, and Ang II-induced activity of mitogen-activated protein kinase was inhibited in left ventricles in the transgenic mice. Although transient outward K+ current recorded in cardiomyocytes from AT2 TG mice was not influenced by AT2 activation, this study suggested that overexpression of AT2 decreases the sensitivity of pacemaker cells to Ang II. Our results demonstrate that stimulation of cardia AT2 exerts a novel antipressor action by inhibiting AT1-mediated chronotropic effects, and that application of AT1 antagonists to patients with cardiovascular diseases has beneficial pharmacotherapeutic effects of stimulating cardiac AT2.

Molecular evolution of duplicated amylase gene regions in Drosophila melanogaster: evidence of positive selection in the coding regions and selective constraints in the cis-regulatory regions.

In this study, we randomly sampled Drosophila melanogaster from Japanese and Kenyan natural populations. We sequenced duplicated (proximal and distal) Amy gene regions to test whether the patterns of polymorphism were consistent with neutral molecular evolution. F(st) between the two geographically distant populations, estimated from Amy gene regions, was 0.084, smaller than reported values for other loci, comparing African and Asian populations. Furthermore, little genetic differentiation was found at a microsatellite locus (DROYANETSB) in these samples (G'st = -0.018). The results of several tests (Tajima's, Fu and Li's, and Wall's tests) were not significantly different from neutrality. However, a significantly higher level of fixed replacement substitutions was detected by a modified McDonald and Kreitman test for both populations. This indicates that positive selection occurred during or immediately after the speciation of D. melanogaster. Sliding-window analysis showed that the proximal region 1, a part of the proximal 5' flanking region, was conserved between D. melanogaster and its sibling species, D. simulans. An HKA test was significant when the proximal region 1 was compared with the 5' flanking region of Alcohol dehydrogenase (Adh), indicating a severe selective constraint on the Amy proximal region 1. These results suggest that natural selection has played an important role in the molecular evolution of Amy gene regions in D. melanogaster.

Evolutionary relationships and sequence variation of alpha-amylase variants encoded by duplicated genes in the Amy locus of Drosophila melanogaster.

To infer the genealogical relationships of alpha-amylase electromorphs of Drosophila melanogaster, we determined the nucleotide sequences of a collection of electromorphs sampled throughout the world. On average there were 1.0 amino acid substitutions between identical electromorphs and 3.9 between different electromorphs, respectively. We found that the evolution of AMY1 through AMY6 electromorphs occurred by sequential accumulation of single amino acid substitutions each causing one charge difference. The nucleotide diversities at synonymous sites within Amy1,Amy2,Amy3,Amy4 and Amy6 were 0.0321, 0.0000, 0.0355, 0.0059 and 0.0030, respectively. We also obtained evidence of genetic exchanges, such as intrachromosomal recombination, interchromosomal recombination or gene conversion, between the two duplicated Amy genes as well as among the alleles.

Characterization of a novel parathyroid hormone (PTH) receptor with specificity for the carboxyl-terminal region of PTH-(1-84)

Carboxyl-terminal fragments of PTH (C-PTH) appear to have biological properties different from those mediated by the amino-terminal portions of PTH and PTH-related peptide (PTHrP). To characterize a C-PTH receptor that may be involved in mediating these functions, we performed RRAs and affinity cross-linking studies with several clonal cell lines. Radiolabeled recombinant [Leu8,18,Tyr34]human PTH-(1-84)[mutPTH-(1-84) and [Tyr34] human PTH-(19-84)[mutPTH-(19-84) showed little or no specific binding to stably expressed recombinant PTH/PTHrP receptors. However, high affinity binding was observed using osteoblast-like and rat parathyroid (PT-r3) cells. The apparent Kd values were 20-30 nM for PTH-(1-84), mutPTH-(1-84), and mutPTH-(19-84), respectively; 400-800 nM for PTH-(39-84); and more than 5000 nM for PTH-(53-84). [Nle8,18,Tyr34]bovine PTH-(1-34)amide [PTH-(1-34)], PTH-(44-68), PTHrP-(37-74), and PTHrP-(109-141) showed no displacement of either radioligand. C-PTH receptor number was increased up to 2-fold by pretreating ROS 17/2.8 cells with increasing doses of PTH-(1-34), PTH-(1-84), or 8-bromo-cAMP, whereas no change was observed in response to dexamethasone or PTH-(39-84). Cross-linking studies using radiolabeled mutPTH-(1-84) or mutPTH-(19-84) revealed specific labeling of two proteins in ROS 17/2.8 cells that were approximately 40 and 90 kilodaltons in size (including the radioligand of approximately 10 kilodaltons). The intensity of affinity labeling of both proteins was dose dependently inhibited by increasing concentrations of unlabeled PTH-(1-84) and several carboxyl-terminal PTH-(1-84) fragments, but not by PTH-(1-34). Similar studies with PT-r3 cells revealed only a single protein band of about 90 kilodaltons. These data indicate that the carboxyl-terminal portion of PTH-(1-84) binds specifically to a unique receptor/binding protein distinct from the previously isolated PTH/PTHrP receptor.

Receptors for the carboxyl-terminal region of pth(1-84) are highly expressed in osteocytic cells.

PTH is a potent systemic regulator of cellular differentiation and function in bone. It acts upon cells of the osteoblastic lineage via the G protein-coupled type-1 PTH/PTH-related peptide receptor (PTH1R). Carboxyl fragments of intact PTH(1-84) (C-PTH fragments) are cosecreted with it by the parathyroid glands in a calcium-dependent manner and also are generated via proteolysis of the hormone in peripheral tissues. Receptors that recognize C-PTH fragments (CPTHRs) have been described previously in osteoblastic and chondrocytic cells. To directly study CPTHRs in bone cells, we isolated clonal, conditionally transformed cell lines from fetal calvarial bone of mice that are homozygous for targeted ablation of the PTH1R gene and transgenically express a temperature-sensitive mutant SV40 T antigen. Cells with the highest specific binding of the CPTHR radioligand (125)I-[Tyr(34)]hPTH(19-84) exhibited a stellate, dendritic appearance suggestive of an osteocytic phenotype and expressed 6- to 10-fold more CPTHR sites/cell than did osteoblastic cells previously isolated from the same bones. In these osteocytic (OC) cells, expression of mRNAs for CD44, connexin 43, and osteocalcin was high, whereas that for alkaline phosphatase and cbfa-1/osf-2 was negligible. The CPTHR radioligand was displaced completely by hPTH(1-84), hPTH(19-84) and hPTH(24-84) (IC(50)s = 20-50 nM) and by hPTH(39-84) (IC(50) = 500 nM) but only minimally (24%) by 10,000 nM hPTH(1-34). CPTHR binding was down-regulated dose dependently by hPTH(1-84), an effect mimicked by ionomycin and active phorbol ester. Human PTH(1-84) and hPTH(39-84) altered connexin 43 expression and increased apoptosis in OC cells. Apoptosis induced by PTH(1-84) was blocked by the caspase inhibitor DEVD. We conclude that osteocytes, the most abundant cells in bone, may be principal target cells for unique actions of intact PTH(1-84) and circulating PTH C-fragments that are mediated by CPTHRs.

The 69-84 amino acid region of the parathyroid hormone molecule is essential for the interaction of the hormone with the binding sites with carboxyl-terminal specificity.

We evaluated the competitive inhibitory effect of intact PTH, the amino-terminal PTH(1-34) fragment, and a series of truncated carboxyl-terminal PTH fragments on the binding of internally 35S-labeled human PTH(1-84) ([35S]hPTH(1-84)) to osteoblastic cells (ROS 17/2.8), in order to identify the minimum and critical elements within the PTH molecule for the interaction with the binding sites specific for the carboxyl-terminal region of the hormone. When the amino-terminal region of the PTH molecule was truncated stepwise, hPTH(35-84), hPTH(53-84) and hPTH(69-84), but not hPTH(70-84), significantly inhibited the [35S]hPTH(1-84) binding. On the other hand, the simple deletion of the carboxyl-terminal glutamine at position 84 of hPTH(53-84) [hPTH(53-83)] resulted in blunting the inhibitory effect of the peptide on the [35S]hPTH(1-84) binding. Furthermore, hPTH(35-84), hPTH(53-84) and hPTH(69-84), but not hPTH(70-84) nor hPTH(53-83), augmented the inhibitory effect of the amino-terminal PTH fragment [hPTH(1-34)] on the [35S]hPTH(1-84) binding. Of special interest was that the combination of hPTH(1-34) and hPTH(35-84) reproduced the inhibitory effect of unlabeled hPTH(1-84) on the [35S]hPTH(1-84) binding, on an equimolar basis. The 69-84 region of the PTH molecule thus appears to be crucial for binding to the carboxyl-terminal specific binding sites for PTH in osteoblasts. The interaction of the amino-terminal and carboxyl-terminal regions of a PTH molecule with their own respective binding sites seemed to occur in a fairly independent manner.

Mechanisms of the anticholinergic effect of SUN 1165 in comparison with flecainide, disopyramide and quinidine in single atrial myocytes isolated from guinea-pig.

1. The mechanism of the anticholinergic effect of SUN 1165 on the acetylcholine (ACh)-induced K+ current (IK.ACh) was examined and compared with those of flecainide, disopyramide and quinidine in single atrial myocytes, in a whole-cell configuration by use of the concentration-jump technique. This technique combines an intracellular perfusion and a rapid exchange of external solution surrounding the voltage-clamped single myocyte within 2 ms. 2. In the cells loaded with guanosine-5'-triphosphate (GTP), 100 microM, the muscarinic ACh response, (IK.ACh), was mediated by GTP-binding proteins. The concentrations of the test drugs that produced a half-maximal inhibition of ACh (1 microM)-induced IK.ACh (IC50) were 29 microM for SUN 1165, 3.6 microM for flecainide, 1.7 microM for disopyramide, and 1.6 microM for quinidine. The blockade of IK.ACh by SUN 1165 and its recovery from the inhibition occurred within a few seconds. Disopyramide had a similar rapid action, while the effects of flecainide and quinidine occurred much more slowly within a few tens of seconds. 3. In cells loaded with 100 microM guanosine-5'-O-(3-thiotriphosphate) (GTP gamma S, a nonhydrolysable GTP analogue), the K+ channel was uncoupled from the muscarinic receptors and activated irreversibly due to direct activation of GTP-binding proteins by GTP gamma S. SUN 1165 and disopyramide had a weak inhibitory effect (IC50 greater than 100 microM for both), while flecainide and quinidine depressed the GTP gamma S-induced K+ current with similar potencies to the cases of ACh-induced currents; IC50 was 5.3 microM for flecainide and 4.4 microM for quinidine. 4 These results suggest that the mechanisms underlying the anticholinergic effects of these antiarrhythmic drugs are different; disopyramide and high concentrations of SUN 1165 mainly block muscarinic ACh receptors in atrial myocytes, while flecainide and quinidine inhibit the K+ channel itself and/or GTP-binding proteins.

Effects of diuretics on GABA-gated chloride current in frog isolated sensory neurones.

1. Effects of three diuretics (furosemide, amiloride and alpha-human atrial natriuretic polypeptide (alpha-hANP] on GABA-activated chloride current (ICl) were investigated in frog isolated sensory neurones, following suppression of Na+, K+ and Ca2+ currents, by use of a 'concentration-clamp' technique. 2. Furosemide inhibited the GABA-activated ICl in a non-competitive manner and facilitated the inactivation phase, while amiloride inhibited the GABA response in a competitive manner, both inhibitions being concentration-dependent. Alpha-hANP had no effects on the GABA-induced ICl. 3. The reversal potential of GABA-activated ICl (EGABA) was not shifted in the presence of amiloride or furosemide. 4. The results suggest that amiloride may act at the GABA binding site while furosemide may act on the GABA-gated chloride channel.

Different time courses of the blockade of sodium current by lignocaine and SUN 1165 in single myocytes isolated from guinea-pig atrium.

1. The time course of the blockade of sodium currents (INa) by the antiarrhythmic agents, lignocaine and SUN 1165, was studied in single myocytes isolated enzymatically from guinea-pig atrium, by a new concentration-jump termed as a 'concentration-clamp' technique. This technique combines an intracellular perfusion and a rapid exchange of external solution surrounding the voltage-clamped myocyte within 2 ms. 2. Lignocaine (3.7 x 10(-5) M to 3.7 x 10(-4) M) inhibited the peak amplitude of INa in a concentration-dependent fashion. It took 2 to 5s to reach apparent steady-state inhibition at the concentrations used. Complete recovery from the inhibition also took 2 to 5s after washing out the agent. In contrast, the inhibitory effect of SUN 1165 (1 x 10(-5) M) on the peak INa gradually progressed and reached a steady-state level about 2 min after the start of drug-application. The recovery required more than 10 min after washing out of the agent. 3. In cardiomyocytes treated with scorpion toxin (5 micrograms ml-1), the inactivation of INa was greatly inhibited, resulting in the relatively persistent Na inward current (persistent INa) during the depolarizing pulse. Lignocaine (1.1 x 10(-4) M) applied during the depolarizing pulse, reduced in a single-exponential fashion the amplitude of the persistent INa in milliseconds. On the other hand, lignocaine applied several tens of milliseconds before the depolarizing pulse induced only a small reduction of the peak amplitude of the first persistent INa. When SUN 1165 (1 x 10- M) was applied during the depolarizing pulse, there was only a small instantaneous reduction of the amplitude of the persistent I'N, although it did inhibit time-dependently, the peak IN.. Both agents accelerated the decay phase of the persistent IN in a time-dependent manner. 4. These results suggest that lignocaine and SUN 1165 may preferentially interact with the openstate of the sodium channel rather than with the rested one, although SUN 1165 does so much more slowly.

Antiarrhythmic agents act differently on the activation phase of the ACh-response in guinea-pig atrial myocytes.

1. Anti-acetylcholine effects of pilsicainide, flecainide, disopyramide and propafenone on the acetylcholine (ACh)-induced K+ current (IK.ACh) were examined in dissociated guinea-pig atrial myocytes under whole-cell voltage clamp by the use of the 'concentration-clamp' technique. 2. The IK.ACh was activated with a latency of about 100 ms after 1 microM ACh application and desensitized to a steady-state level. The latent period and the time to peak response were shortened with increasing ACh concentration. 3. The values of half-maximal inhibition (IC50) on the peak and steady state responses were 25 and 25 microM for pilsicainide, 1.7 and 2.0 microM for disopyramide, 19 and 2.0 microM for flecainide and 0.7 and 0.2 microM for propafenone, respectively. 4. Pilsicainide and disopyramide increased the latent period and the time to peak of IK.ACh in a concentration-dependent manner. Flecainide and propafenone did not change the latent period, but shortened the time to peak and hastened the decay of IK.ACh in a voltage-independent manner. 5. The results suggest that the mechanisms underlying the anti-acetylcholine effect of antiarrhythmic drugs are different among these drugs: i.e., pilsicainide and disopyramide mainly block the muscarinic ACh receptors while flecainide and propafenone inhibit the K+ channel itself as open channel blockers.

Intracellular picrotoxin blocks pentobarbital-gated Cl- conductance.

Using the 'inside-out' configuration of frog sensory neurons, we studied the effect of intracellular picrotoxin on the pentobarbital-gated single channel response of Cl- -current (iCl). The pentobarbital-induced iCl showed no voltage-dependency and the single channel conductance (gamma Cl) was 16 +/- 3.1 pS (n = 6). Picrotoxin caused the pentobarbital-gated Cl- channels to react in a flickering pattern and then finally caused them to cease their opening altogether. This inhibitory action of picrotoxin was reversible.

The anion selectivity of the gamma-aminobutyric acid controlled chloride channel in the perfused spinal ganglion cell of frog.

The selectivity of the GABA-controlled Cl- channel in the membrane of the dorsal root ganglion cell of the frog has been measured in internally perfused cells by means of current and voltage clamp. When Cl- was replaced by various anions, the 10(-5) or 10(-4) M GABA-induced reversal potentials (EGABA) for Br-, I-, NO3-, ClO4-, SCN-, BF4- and ClO3- were more negative than that for Cl-, despite the fact that, in solution, the test anions are either larger than or similar in size to Cl-.

Changes of electroretinogram and neurochemical aspects of GABAergic neurons of retina after intraocular injection of kainic acid in rats.

The effect of kainic acid (KA) on both electroretinogram (ERG) readings and neurochemical properties of the retina was investigated in rats with emphasis placed upon examination of the events that occur immediately following KA treatment. KA was injected into the eyes of rats with doses of 50 and 200 nmol. One hour after injection, histological alterations became evident. Swelling was observed in the inner and outer plexiform layers. Certain ganglion cells and cells of the inner nuclear layers exhibited pyknotic nuclei. Most of the ganglion cells appeared to have degenerated 48 h following injection, and the form of the outer plexiform layer was incomplete. The amplitude of the b-waves of the ERG decreased 2 h following injection and never recovered. The amplitude of the a-waves was unaffected by KA. The gamma-aminobutyric acid content in the eyecups began to decrease within 1 h and fell to approximately 20% of its original level 24 h following injection. The taurine content in the eyecups was unaffected by KA. The activity of glutamic acid decarboxylase remained unaffected for 2 h after injection, but was reduced to approximately 40% of its original activity by 24 h after injection. A possible explanation for the mechanism by which KA effects degenerative changes in the rat retina is that KA induces release of neurotransmitters through stimulation of neurons, and degeneration in the soma follows.

Mechanism of inhibition by SUN 1165, a new Na channel blocking antiarrhythmic agent, of cardiac glycoside-induced triggered activity.

The mechanism of the antiarrhythmic action of SUN 1165, a selective Na channel blocker, in digitalis-induced arrhythmias was investigated by means of conventional microelectrode and suction pipette methods with isolated canine Purkinje fibers and guinea-pig single ventricular cells, respectively. SUN 1165 decreased acetylstrophanthidin-induced delayed afterdepolarization and completely blocked the initiation of triggered activity by acetylstrophanthidin in Purkinje fibers. Delayed afterdepolarization, which was completely abolished either by intracellular dialysis with EGTA or by extracellular superfusion with caffeine, was decreased by SUN 1165 in a concentration-dependent manner in single ventricular cells. These results suggest that an increase in intracellular Ca2+ concentration is a requirement for delayed afterdepolarization. Furthermore, the antiarrhythmic action of SUN 1165 in cardiac glycoside-induced arrhythmias in dogs could be mediated not only by an inhibition of sodium channels and subsequent reduction in the intracellular sodium activity, but also by a reduction of intracellular calcium activity due to the Na+-Ca2+ exchange mechanism.

Effect of human plasma-type platelet-activating factor acetylhydrolase in two anaphylactic shock models.

The effect of human recombinant plasma-type platelet-activating factor (PAF) acetylhydrolase was examined in two murine models, PAF-induced death and active anaphylactic models. In the PAF-induced death model where mice were injected intravenously with 40 microg/kg of PAF, the administration of PAF acetylhydrolase reduced mortality in a dose-dependent manner, showing complete prevention of mortality at 1.0 mg/kg. Myeloperoxidase activity, the marker for neutrophils, was increased in the lung by PAF injection, and the PAF acetylhydrolase treatment significantly reversed the increase in myeloperoxidase activity. As in the PAF-induced model, PAF acetylhydrolase also decreased mortality in the active anaphylactic shock model where bovine serum albumin was injected intravenously to mice previously immunized with bovine serum albumin. The protective effect of PAF acetylhydrolase on mortality in this model was significant at 1.0 mg/kg. These results suggest that PAF is an important mediator in the lethality of systemic anaphylaxis, and that PAF acetylhydrolase may be beneficial for treatment of anaphylactic shock.

Protective effect of alpha-human atrial natriuretic polypeptide (alpha-hANP) on chemical-induced pulmonary edema.

It has been established that alpha-hANP, the newly discovered peptide extracted from human cardiac atria, has potent natriuretic and hypotensive actions. Our present investigation is the first to demonstrate that alpha-hANP is capable of protecting against pulmonary edema caused by various chemicals, using isolated perfused guinea pig lung system. Lungs were perfused via pulmonary artery with Krebs-Ringer bicarbonate buffer at 5.0 ml/min, and wet weight of lungs and perfusion pressure of pulmonary artery (Pa) were monitored. Bolus injection of Triton-X or CHAPS into cannulated pulmonary artery produced edema as indicated by a massive increase in wet weight and a slight increase in Pa. Constant infusion of alpha-hANP through pulmonary artery at 200 ng/ml was effective in causing decrease in wet weight of lung. Perfusion of lung with paraquat or PGF2 alpha, and repeated bolus injection of arachidonic acid or PGE2 caused elevation in both wet weight of lung and Pa. The treatment with alpha-hANP similar to that described above also protected against edema caused by paraquat or arachidonic acid. Bolus administration of epinephrine induced a slight increase in wet weight and Pa, and alpha-hANP was effective in decreasing the elevated lung wet weight and Pa of lungs. Infusion or bolus administration of alpha-hANP into control lungs increased cGMP level in outflow perfusate as well as in lung tissue significantly. In lungs with edema which were induced by Triton-X or paraquat, there was a slight increase in cGMP level in Triton-X treated and no increase in paraquat treated lung tissues. In either cases, was there any increase in cGMP level in perfusate. The specific binding study of [125I]alpha-hANP revealed that the lack of increase in cGMP was not due to a loss of receptor in Triton-X or paraquat treated lungs. Thus our study demonstrated that alpha-hANP had a direct anti-edematic action(s) in lung which was not secondary to the systemic natriuretic and/or hypotensive action(s).

Autoimmune vesicles on the face and neck. A variant of Brunsting-Perry type localized bullous pemphigoid?

We report a case of blistering disease presenting a unique distribution of vesiculobullous lesions on the face and neck which is similar to Brunsting-Perry type of localized bullous pemphigoid (BP). Histopathology of a lesional skin biopsy demonstrated a subepidermal blister. Direct immunofluorescence demonstrated a strong linear deposition of IgG and IgA to the basement membrane zone, and a faint staining for C3. However, circulating antibodies were not detected by indirect immunofluorescence and immunoblotting. And the patient did not develop atrophic scars and was a relatively young woman. This case might be a variant of Brunsting-Perry type of localized BP or localized epidermolysis bullosa acquisita, presenting the clinical heterogeneity of subepidermal blistering diseases.

[Isoproterenol continuous nebulization of childhood status asthmaticus. II. Efficacy and side effects of low-dose method comparing with high-dose method].

We investigated the efficacy and side effects of "low-dose isoproterenol continuous nebulization" for childhood status asthmaticus, and compared them with those of "high-dose method". "Low-dose" is defined as 10 ml or less of 0.5% dl-isoproterenol solution diluted in 500 ml of normal saline. Subjects were 23 children who were hospitalized and underwent the nebulization therapy. The period of continuous nebulization was 26.3 +/- 12.5 hours. The Wood's clinical score clearly decreased in 22 cases, the average score changing from 7.3 +/- 1.2 to 2.8 +/- 1.5. Heart rate was not elevated significantly during the nebulization period, and decreased gradually (142 +/- 22/min at the start of the nebulization, 145 +/- 22/min at 1 hour, and 134 +/- 23/min at 3 hours, and 103 +/- 13/min at the cessation of the nebulization). Serum GOT, LDH, CPK, and potassium were decreased after the nebulization compared with the values before the treatment, the changes of the last 2 items being statistically significant. Two subjects who had vomited before the nebulization therapy complained nausea during the procedure, and one experienced transient finger tremor. We conclude that "low-dose isoproterenol continuous nebulization" is an effective and safe method for childhood status asthmaticus. We expect that this method will be familiar to all clinicians.