Biomedical subjects

R J Martin

Publications and source records attributed to R J Martin.

At least 145 records · Page 8Linked to original sources

PubMed1997

Further studies on the chronotherapy of asthma with inhaled steroids: the effect of dosage timing on drug efficacy.

BACKGROUND: Chronotherapy studies with inhaled corticosteroids have shown optimal therapeutic benefit when steroids are administered four times per day (QID) or once daily at 3 PM. OBJECTIVE: This study evaluated whether more convenient once-daily dosage times (8 AM and 5:30 PM) produce improvement in asthma equivalent to QID. METHODS: Efficacy outcome measures included FEV1, peak expiratory flow rates, bronchial responsiveness, use of beta2-agonists, nocturnal awakenings, and responses to a quality of life questionnaire. Systemic effects were blood eosinophil count, cortisol level, 24-hour urinary cortisol, and evaluation for oral candidiasis and dysphonia. RESULTS: Baseline measurements for all three treatment groups were similar. For morning peak expiratory flow rate, significant improvement was seen for the QID group (p = 0.001) and the 5:30 PM group (p = 0.003), but not the 8 AM group (p = 0.75). For evening peak expiratory flow rate, significant improvement was seen for the QID group (p = 0.005) and the 5:30 PM group (p = 0.01), but not for the 8 AM group (p = 0.47). There were significant improvements in all other outcome variables for each group except PC20. There was a significant improvement in PC20 only in the QID group. The systemic effects of the three regimens were comparable. CONCLUSION: Dosing of inhaled steroid at 5:30 PM had no increased systemic effects and produced efficacy similar to QID dosing. Dosing at 8 AM did not produce results consistently comparable to QID dosing. Optimal once-daily dosing of inhaled steroid is between 3 PM and 5:30 PM.

Administration, Inhalation↗

PubMed1997

Modes of action of anthelmintic drugs.

Modes of action of anthelmintic drugs are described. Some anthelmintic drugs act rapidly and selectively on neuromuscular transmission of nematodes. Levamisole, pyrantel and morantel are agonists at nicotinic acetylcholine receptors of nematode muscle and cause spastic paralysis. Dichlorvos and haloxon are organophosphorus cholinesterase antagonists. Piperazine is a GABA (gamma-amino-butyric acid) agonist at receptors on nematode muscles and causes flaccid paralysis. The avermectins increase the opening of glutamate-gated chloride (GluCl) channels and produce paralysis of pharyngeal pumping. Praziquantel has a selective effect on the tegument of trematodes and increases permeability of calcium. Other anthelmintics have a biochemical mode of action. The benzimidazole drugs bind selectively to beta-tubulin of nematodes, cestodes and fluke, and inhibit microtubule formation. The salicylanilides: rafoxanide, oxyclozanide, brotianide and closantel and the substituted phenol, nitroxynil, are proton ionophores. Clorsulon is a selective antagonist of fluke phosphoglycerate kinase and mutase. Diethylcarbamazine blocks host, and possibly parasite, enzymes involved in arachidonic acid metabolism, and enhances the innate, nonspecific immune system.

Animals↗

PubMed1997

A vesicle preparation for resolving single-channel currents in tegument of male Schistosoma mansoni.

A tegumental vesicle preparation from adult male Schistosoma mansoni was developed that allows the resolution of single ion-channel currents. Adult male schistosomes were exposed to a low pH (3.75) medium for a period of approximately 30 min at 37 degrees C. During this period smooth vesicles formed from the tegument. Fluorescence microscopy following staining of the tegument with the dye, 5-N-[octadecanoyl]aminofluorescein (AF-18), transmission electron microscopy and scanning electron microscopy revealed that the vesicles were produced from the outer tegumental membrane. The fluorescence studies showed the presence of the double bilayer structure of the outer membrane in > 41% of the vesicles. These studies suggested that the preparation is suitable for single-channel recording with the patch-clamp technique. Cell-attached and isolated inside-out patch recordings of ion-channel activity were obtained with giga-ohm resistance seals. Different types of ion-channel were recorded from tegumental vesicles from male schistosomes, illustrating the potential of the technique. The channels observed included: a non-selective cation channel (360 pS); a K+ channel (with a conductance of 115 pS in high bath-K conditions); and a Cl- selective channel (20 pS). The currents of these ion-channels may cross the double bilayer of the outer tegumental membrane.

Animals↗

PubMed1997

Effect of hyperoxia on substance P expression and airway reactivity in the developing lung.

This study was undertaken to characterize changes in the tachykinin system induced by hyperoxic exposure and the potential effects on airway contractile responses. We exposed 7-day-old rat pups to either room air or hyperoxia (> 95% O2) for 7 days to assess pulmonary beta-preprotachykinin (beta-PPT) gene expression, substance P (SP) levels, and airway contractile responses to cholinergic stimulation before and after neurokinin-1 (NK1) receptor blockade. Lung beta-PPT mRNA expression, lung and tracheal SP levels, and contractile responses to exogenous acetylcholine and electrical field stimulation were measured in vitro in normoxia- and hyperoxia-exposed tracheal cylinders. Hyperoxia caused a 1.1- to 2.6-fold increase in steady-state lung beta-PPT mRNA and a 50 and 32% increase in SP levels of lung and trachea, respectively. In response to cholinergic stimulation, maximal contractile force (Emax) of hyperoxia exposed tracheal muscle was significantly higher than for normoxic controls. Addition of the SP (NK1) receptor blocker CP-99994 (10 microM) decreased sensitivity to electrical field stimulation in both hyperoxic and normoxic trachea without a significant decline in Emax. These data provide evidence for both increased SP production and enhanced maximal contractile responses of hyperoxia-exposed neonatal trachea to cholinergic stimulation. The tachykinin peptide SP does not, however, appear to play a major role in the enhanced airway reactivity associated with hyperoxic lung injury during early postnatal life.

Acetylcholine↗

PubMed1997

Role of endogenous NO in modulating airway contraction mediated by muscarinic receptors during development.

We sought to characterize the role of endogenous nitric oxide (NO) released from airway epithelium in attenuating tracheal smooth muscle (TSM) contraction induced by exposure to acetylcholine (ACh). Organ bath experiments were performed on TSM from young pigs of three ages (3-7 days, 2-3 wk, and 3 mo). Concentration-response curves to cumulative doses of ACh (10(-8) to 10(-4) M) were generated before and after addition of the NO synthase blocker N omega-nitro-L-arginine methyl ester (L-NAME). L-NAME caused a significant increase in cholinergic sensitivity (decrease in 50% effective dose) at 3-7 days and 2-3 wk but not 3 mo. Maximum responses to ACh increased after L-NAME at all three ages. Removal of tracheal epithelium caused a significant increase in sensitivity to ACh at all ages, which progressively declined with advancing age. In the absence of epithelium, L-NAME no longer influenced contractile responses to ACh. Density of M3 muscarinic receptors in tracheal epithelium was upregulated in the youngest piglets. We conclude that, under in vitro conditions, release of endogenous NO opposes cholinergically induced contraction of piglet TSM. This phenomenon diminishes with advancing postnatal age, requires an intact airway epithelium, and correlates with upregulation of M3 muscarinic receptors in airway epithelium. We speculate that NO may play a useful role in attenuating cholinergically mediated airway smooth muscle contraction in early life when pulmonary function is characterized by high airway resistance.

Acetylcholine↗

PubMed1997

Expression of IL-12 and IL-13 mRNA in asthma and their modulation in response to steroid therapy.

Interleukin-12 (IL-12) and IL-13 are two recently characterized cytokines which play an important role in the induction of T helper cell type 1 (Th1-) and Th2-like cells, respectively. Using the technique of in situ hybridization, we have investigated the expression of these cytokines in bronchial biopsies from nine allergic asthmatics and nine normal control subjects. To determine the effect of steroid therapy on the expression of IL-12 and IL-13 in asthma, the numbers of cells expressing these cytokine mRNA before and after a 1-wk course of oral prednisone in six steroid-sensitive (SS) and five steroid-resistant (SR) moderately severe asthmatics were also examined. There was an increased number of IL-13, and a decreased number of IL-12 mRNA positive cells in asthmatic subjects compared with normal control subjects (p < 0.001). After steroid treatment, the increase in FEV1 values observed in SS asthmatics was accompanied by a significant decrease in cells expressing IL-13 mRNA (p < 0.05) and an increase in the numbers of cells expressing IL-12 mRNA (p < 0.05). In contrast, steroid therapy in SR asthmatics was not associated with significant changes in IL-12 and IL-13 mRNA expression. Thus, allergic asthma is associated with a downregulation of IL-12 mRNA expression and an upregulation of IL-13 mRNA expression. These results suggest an in vivo role for IL-12 and IL-13 in modulating allergic responses and support the notion that the clinical effects of glucocorticoids are at least partially mediated through the modulation of cytokine production.

Adult↗

PubMed1997

Quality control of peak flow meters for multicenter clinical trials. The Asthma Clinical Research Network (ACRN).

Although peak expiratory flow (PEF) measurements are recommended for monitoring and assessing treatment of asthmatic patients, and widely employed to assess outcome in clinical trials and epidemiologic studies, information about performance of peak flow meters (PFM) under field conditions is lacking. We describe a simple testing system consisting of a testing chamber, a spirometer, and a calibration syringe to evaluate the relative accuracy or median relative bias (MRB), precision, or inter-quartile range (IQR) of the mini-Wright PFM. The relative accuracy ranged from -4.4 to 13.2% (mean, 4.1%) and the precision from 0.06 to 11.5% (mean, 1.2%). Durability of this PFM was assessed during a 26-wk clinical trial in 255 asthmatic subjects at five centers. Seventy-one PFM (19.9%) were identified as having failed to meet acceptance criteria, predominantly because of loss of relative accuracy, by the clinics at follow-up visits (n = 36), and by the Data Coordinating Center on retrospective review of quality control measurements submitted by the clinics (n = 35). This study indicates that a simple device can be used to evaluate the relative accuracy and precision of a given PFM and to ensure the quality of PEF measurements during a clinical trial. To the extent that one can extrapolate these data to other devices, our findings indicate that the failure rate of PFM over time can be high, indicating that quality control of a PFM over time is absolutely essential in clinical trials as well as in routine clinical care.

Asthma↗

PubMed1997

Bronchoscopic evaluation of severe asthma. Persistent inflammation associated with high dose glucocorticoids.

The role of inflammation in the pathogenesis of severe asthma chronically treated with high doses of glucocorticoids is poorly understood. Despite this, treatment has been aimed at advancing anti-inflammatory and immunomodulator therapy. This study was designed to evaluate both the presence and type of airway inflammation in patients with severe asthma. A prospective bronchoscopic study evaluated 14 severe, high-dose oral glucocorticoid dependent asthmatics. Bronchoalveolar lavage fluid was analyzed for cytology and inflammatory mediators. Endobronchial and transbronchial biopsies were performed in selected patients for morphometric evaluation of macrophage/monocytes, neutrophils, eosinophils and lymphocytes. These results were compared with lavage and endo- and transbronchial biopsy studies in normal controls and patients with moderate asthma. The concentration of eosinophils in bronchoalveolar lavage fluid was highest in the moderate asthmatics not on glucocorticoids, with very little difference between normal controls and severe asthmatics (significant difference among the groups, p = 0.007). In contrast, the severe asthmatics demonstrated a twofold higher concentration of neutrophils in lavage than either the mild-moderate asthmatics, or the normal controls (p = 0.032 among the groups, p < 0.05 between the severe asthmatics and both controls). Similar results were obtained in the endobronchial and transbronchial biopsy specimens, which consistently showed significantly higher numbers of neutrophils in the severe asthmatics than in the control groups. The eicosanoid mediators, thromboxane and leukotriene B4, were also highest in the severe asthma group (differences among the groups, p = 0.019 and p = 0.023, respectively). These findings suggest that inflammation remains in severe symptomatic asthmatics despite treatment with high dose glucocorticoids which may be due to the severity of disease, glucocorticoid treatment, or other as yet undefined factors.

Administration, Oral↗

PubMed1997

An evaluation of colchicine as an alternative to inhaled corticosteriods in moderate asthma. National Heart, Lung, and Blood Institute's Asthma Clinical Research Network.

Colchicine demonstrates an array of anti-inflammatory properties of potential relevance to asthma. However, the efficacy of colchicine as an alternative to inhaled corticosteroid therapy for asthma is unknown. Five centers participated in a controlled trial testing the hypothesis that in patients with moderate asthma needing inhaled corticosteroids for control, colchicine provides therapeutic benefit as measured by maintenance of control when inhaled steroids are discontinued. Subjects were stabilized on triamcinolane acetonide (800 microg daily) and then enrolled in a 2-wk run-in during which all subjects took both colchicine (0.6 mg/twice a day) and triamcinolone. At the end of the run-in, all subjects discontinued triamcinolone and were randomized to continued colchicine (n = 35) or placebo (n = 36) for a 6-wk double-blind treatment period. The treatment groups were similar in terms of disease severity. After corticosteroid withdrawal, 60% of colchicine-treated and 56% of placebo-treated subjects were considered treatment failures as defined by preset criteria. No significant difference in survival curves was found between treatment groups (log rank = 0.38). Other measures, including changes in FEV1, peak expiratory flow, symptoms, rescue albuterol use, and quality of life scores, also did not differ between groups. Of note, subjects failing treatment had significantly greater methacholine responsiveness at baseline than did survivors (PC20, 0.81+/-1.38 versus 2.11+/-2.74 mg/ml; p = 0.01). An analysis of treatment failures suggested that the criteria selected for failure reflected a clinically meaningful but safe level of deterioration. We conclude that colchicine is no better than placebo as an alternative to inhaled corticosteroids in patients with moderate asthma. Additionally, we conclude that the use of treatment failure as the primary outcome variable in an asthma clinical trial where treatment is withdrawn is feasible and safe under carefully monitored conditions.

Administration, Inhalation↗

PubMed1997

Eosinophil-associated TGF-beta1 mRNA expression and airways fibrosis in bronchial asthma.

The histopathology of bronchial asthma is associated with structural changes within the airways, including subepithelial fibrosis, as well as chronic eosinophilic inflammation. The mechanisms responsible for this tissue remodeling, and in particular the role of inflammatory cells, remain to be established. Transforming growth factor-beta (TGF-beta) is a potent profibrotic cytokine which may contribute to the thickening of the reticular lamina by the deposition of collagen fibers. To investigate the molecular mechanisms underlying these structural changes, we have investigated the expression of TGF-beta1 mRNA and immunoreactivity within the bronchial mucosa of mild to severe asthmatic individuals and normal control subjects using the techniques of in situ hybridization and immunocytochemistry. As eosinophils are prominent within the asthmatic airway and are known to synthesize pro-inflammatory cytokines, the presence of TGF-beta1 mRNA and immunoreactive protein in eosinophils was also examined. Asthmatic individuals exhibited a greater expression of TGF-beta1 mRNA and immunoreactivity in the airways submucosa than normal control subjects (P < 0.05), and these increases were directly related to the severity of the disorder. The extent of airways fibrosis, as detected histochemically, was also increased in asthmatics compared with normal control subjects (P < 0.005). In asthmatic subjects, the presence of subepithelial fibrosis was associated with the severity of the disease and correlated with the decline in forced expiratory volume in 1 s (r2 = 0.78; P < 0.05). Within the asthmatic airways, EG2-positive eosinophils represented the major source of TGF-beta1 mRNA and immunoreactivity. These results provide evidence that TGF-beta1 may play a role in the fibrotic changes occurring within asthmatic airways and that activated eosinophils are a major source of this cytokine.

Adult↗

PubMed1997

Effect of exogenous and endogenous nitric oxide on the airway and tissue components of lung resistance in the newborn piglet.

Despite widespread reports of the vasodilatory actions of nitric oxide (NO), little is known of the relaxant effect of NO on newborn airways or lung parenchymal structures. We studied the effects of inhaled NO at 20, 40, and 80 ppm on lung (Rl), tissue (Rti), and airway (R(aw)) resistance in 13 2-5-d-old anesthetized, ventilated, open-chested piglets. Rl was measured from transpulmonary pressure and air flow. Rti was measured by alveolar capsules, and R(aw) was calculated as the difference between Rl and Rti. Any given concentration of inhaled NO (20, 40, or 80 ppm) significantly decreased Rl (p < 0.001), Rti (p < 0.001), and R(aw) (p < 0.05). In addition, blockade of endogenous NO with 30 mg/kg N omega-nitro-L-arginine methyl ester (L-NAME) given i.v. in 12 piglets significantly increased Rti and Rl with variable changes in R(aw), and caused a decrease in dynamic compliance. Readministration of NO to eight piglets induced a significant decreased in Rl and Rti at 20 and 80 ppm, whereas R(aw) significantly decreased only at 80 ppm. Pulmonary arterial pressure decreased after exposure to inhaled NO and increased after L-NAME administration. Systemic arterial pressure was unaffected by inhaled NO but increased after L-NAME administration. Our results indicate that Rl, R(aw), and Rti are reduced by exogenous NO, suggesting NO-mediated airway smooth muscle relaxation throughout the newborn lung. In contrast, blockade of endogenous NO significantly increases only Rti, suggesting a physiologic role for endogenous NO in regulation of peripheral contractile elements. We speculate that NO-mediated modulation of resistance in pulmonary parenchyma may serve to regulate the balance of ventilation and perfusion and resultant gas exchange in the lungs during early postnatal development.

Airway Resistance↗

PubMed1997

The effect of salmeterol on nocturnal symptoms, airway function, and inflammation in asthma.

STUDY OBJECTIVE: To determine the efficacy of salmeterol alone in a group of patients with moderate asthma with nocturnal worsening of symptoms. DESIGN: Double-blind, randomized, placebo-controlled crossover study. SETTING: Tertiary care hospital specializing in respiratory diseases. PARTICIPANTS: Ten patients with nocturnal asthma. INTERVENTIONS: Subjects were randomized to salmeterol, 100 micrograms twice daily, or placebo for 6 weeks with a 1-week washout between treatment periods. Symptoms, nocturnal awakenings, and beta 2-agonist use were recorded daily. Spirometry was performed at weeks 1 and 6 of each period at bedtime and at 4 AM, and methacholine challenge was performed at 4 AM followed by bronchoscopy with BAL. BAL fluid analysis included cell count and differential count, eosinophil cationic protein, Charcot-Leyden crystal protein, leukotriene B4, and thromboxane B2. RESULTS: The percentage of nights with awakenings decreased significantly with salmeterol (69.8 +/- 8.7% vs 30.6 +/- 10.8% for placebo and salmeterol, respectively; p = 0.02). The percentage of 24-h days with supplemental inhaled beta 2-agonist use significantly decreased with salmeterol (85.9 +/- 9.4% vs 70.4 +/- 10.1% for placebo and salmeterol, respectively; p = 0.04). There were no significant differences in bronchial reactivity, 4 AM FEV1, overnight percentage change in FEV1, or indexes of airway inflammation. CONCLUSIONS: Salmeterol alone improves the number of nocturnal awakenings and supplemental 24-h beta 2-agonist use in nocturnal asthma without significantly altering lung function and airway inflammation.

Adrenergic beta-Agonists↗

PubMed1997

Methacholine challenge testing: safety of low starting FEV1. Asthma Clinical Research Network (ACRN).

STUDY OBJECTIVE: The lower limit for the baseline value to initiate methacholine bronchial hyperresponsiveness testing has not been well established. Recommendations have varied from > 1 L to above 80% of predicted. The objective was to determine if an FEV1 < 60% predicted was acceptable. DESIGN: Retrospective analysis of challenges in 88 patients with a baseline FEV1 of < 60% predicted (mean=45.8%; range, 22 to 59%. SETTING: Academic institutions. RESULTS: There were only four individuals whose FEV1 did not return to > 90% of baseline following one poststudy beta2-agonist treatment. All four responded to a second treatment. There were no adverse sequelae following challenge in any individual. Neither age (up to 79 years) nor gender influenced outcome. CONCLUSIONS: In chronic moderate to severe asthma, it appears that bronchial hyperresponsiveness testing can be safely performed even in those patients with a low baseline FEV1.

Adrenergic beta-Agonists↗

PubMed1997

Evidence for a central mechanism of obesity in the Zucker rat: role of neuropeptide Y and leptin.

Thirty-five years ago, Lois and Theodore Zucker reported the discovery of a genetic mutation in the rat that resulted in juvenile-onset obesity, increased food intake, decreased energy expenditure, and insulin resistance. The mutation was called fatty (fa). The fatty gene is passed on to successive generations by an autosomal recessive mode of inheritance. In the intervening years, much work has been done to characterize the many abnormalities of this animal model of obesity. Nearly 10 years ago, we reviewed the evidence for a central nervous system mechanism in the etiology of obesity in the fatty Zucker rat. Since that time, the discovery of novel peptides and genes has revolutionized the study of the etiology of genetically linked obesities. In this review, we update the evidence for a central nervous system mechanism of obesity in Zucker rats by focusing on the possible role of neuropeptide Y (NPY) and leptin in the etiology of obesity. We also discuss the role of glucocorticoids and insulin in the regulation of NPY.

Animals↗

PubMed1997

Target sites of anthelmintics.

This paper reviews sites of action of anthelmintic drugs including: (1) levamisole and pyrantel, which act as agonists at nicotinic acetylcholine receptors of nematodes; (2) the avermectins, which potentiate or gate the opening of glutamategated chloride channels found only in invertebrates; (3) piperazine, which acts as an agonist at GABA gated chloride channels on nematode muscle; (4) praziquantel, which increases the permeability of trematode tegument to calcium and results in contraction of the parasite muscle; (5) the benzimidazoles, like thiabendazole, which bind selectively to parasite beta-tubulin and prevents microtubule formation; (6) the proton ionophores, like closantel, which uncouple oxidative phosphorylation; (7) diamphenethide and clorsulon, which selectively inhibit glucose metabolism of Fasciola and; (8) diethylcarbamazine, which appears to interfere with arachidonic acid metabolism of filarial parasites and host. The review concludes with brief comments on the development of anthelmintics in the future.

Amino Acid Sequence↗

PubMed1996

Comparison of regularly scheduled with as-needed use of albuterol in mild asthma. Asthma Clinical Research Network.

BACKGROUND: Inhaled beta-agonists are the most commonly used treatment for asthma, but data suggest that regularly scheduled use of these agents may have deleterious effect on the control of asthma. We compared the effects of regularly scheduled use of inhaled albuterol with those of albuterol used only as needed in patients with mild chronic, stable asthma. METHODS: In a multicenter, double-blind study, we randomly assigned 255 patients with mild asthma to inhale albuterol either on a regular schedule (126 patients) or only as needed (129 patients). The patients were followed for 16 weeks. RESULTS: The primary outcome indicator, peak expiratory air flow measured in the morning, did not change significantly during the treatment period in the scheduled (416 liters per minute after the run-in period and 414 liters per minute after the treatment period) or the as-needed (424 liters per minute at both times) treatment groups (P=0.71). There were no significant differences between the two groups in peak flow variability, forced expiratory volume in one second, the number of puffs of supplemental albuterol needed, asthma symptoms, asthma quality-of-life score, or airway responsiveness to methacholine. The statistically significant differences between the groups in evening peak flow and in the short-term bronchodilator response to inhaled albuterol were small and judged to be clinically unimportant. CONCLUSIONS: In patients with mild asthma, neither deleterious nor beneficial effects derived from the regular use of inhaled albuterol beyond those derived from use of the drug as needed. Inhaled albuterol should be prescribed for patients with mild asthma on an as-needed basis.

Administration, Inhalation↗

PubMed1996

Managing the patient with intractable asthma.

Patients first should be evaluated for a mimicking or coexisting condition, such as vocal cord dysfunction or endobronchial stenosis. Once the diagnosis is clearly established and any triggering factors have been addressed, chronotherapy is the key to management--that is, timing drug delivery so that serum levels peak when disease manifestations are at their worst, often in the middle of the night.

Adult↗

PubMed1996

Characterization of whole-cell currents in mucosal and connective tissue rat mast cells using amphotericin-B-perforated patches and temperature control.

Rat mucosal type mast cells are thought to possess only a K+-selective inwardly rectifying (IRK) current in the resting state. We used rat-bone-marrow-derived mast cells (BMMCs) as a model of mucosal mast cells and recorded whole-cell membrane currents from cells perforated with amphotericin B. Under these conditions, both inwardly rectifying (IR) and outwardly rectifying (OR) currents were observed. The reversal potential and conductance of the IR current depended on the extracellular K+ concentration, indicating that the channel was K+ selective. The OR current was not affected by changes in extracellular K+ concentration, but lowering extracellular Cl- concentration reduced the conductance and shifted the reversal potential in a positive direction. The OR current was not affected by K+ channel blockers, but was reversibly blocked by the chloride channel blocker 4,4'-diisothiocyanato-2,2'-stilbenedisulphonate (DIDS), again indicating a Cl- conductance. The IRK current was also detected in the majority of cells using the conventional whole-cell recording configuration at room temperature. In contrast, the ORCl current was only observed in 7% of recordings made at room temperature with the conventional whole-cell voltage-clamp mode, but was detected in 66% of cells if the bath temperature was increased and the integrity of the cell's cytoplasm was preserved by using the perforated-patch technique. Under similar conditions, the ORCl current was also present in rat peritoneal mast cells, a connective tissue phenotype previously thought to have no whole-cell currents in the resting state. The role of this current and factors affecting its activation are discussed.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗