Safety of nifedipine in subjects with bronchial asthma and COPD

This prospective study was undertaken to evaluate the safety of nifedipine, a calcium channel blocking agent, on 60 subjects with asthma, chronic obstructive pulmonary disease (COPD), angina, and normal subjects. All subjects received nifedipine, 20 mg, sublingually. Spirometry was done pre-drug administration and every 20 minutes after for two hours. Parameters measured were forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and forced expiratory flow at 25 percent to 75 percent of total volume (FEF25-75%). Subjects with asthma and COPD were also given nifedipine 20 mg three times daily, orally for two weeks, and tested biweekly during this period. All bronchodilators, beta-blockers, and long acting nitrates were withheld for five half-lives of the drug prior to test day. There was no adverse effect on the pulmonary function. We found a statistically significant improvement (p less than 0.05) in FEV1 after nifedipine. There was no tachyphylaxis at the end of two weeks. Nifedipine is safe in patients with asthma and/or chronic bronchitis.

Evidence for a similar receptor site for binding of [3H] leukotriene E4 and [3H] leukotriene D4 to the guinea-pig crude lung membrane

To determine whether the action of leukotriene E4 is mediated by its cross reaction with leukotriene D4 receptor sites, we compared [3H] leukotriene E4 and [3H]leukotriene D4 binding activities in selected tissues as well as their competition results in the guinea-pig crude lung membrane. We demonstrated good correlation of [3H]leukotriene E4 and [3H]leukotriene D4 binding activities among the tissues studied. A significant correlation was demonstrated between the ability of leukotriene C4, D4 and E4, FPL-55712 and arachidonic acid to inhibit lung [3H]leukotriene E4 and [3H]leukotriene D4 binding. These correlations suggest that leukotriene E4 binds to a site which is similar to or close to the leukotriene D4 receptor.

Specificity and sensitivity of methacholine inhalation challenge in normal and asthmatic children

The provocative dose of inhaled methacholine required to cause a 20% drop in the forced expiratory volume in 1 sec was evaluated in two selected pediatric populations. On the basis of a standardized respiratory questionnaire, 165 individuals 5 to 21 yr of age were identified. Included were 110 normal nonatopic individuals and 55 current asthmatic subjects. Methacholine inhalation challenges were performed by use of a standard inhalation procedure. Fifty-four (98.1%) of the asthmatic subjects responded to methacholine with a 20% drop in the forced expiratory volume in 1 sec. Seventy (63.1%) of the normal individuals did not respond to methacholine. The specificity and sensitivity of the methacholine challenge was best obtained at a provocative dose of 100 breath units of methacholine.

Lymphocyte glucocorticoid receptors in asthmatic and control subjects

Glucocorticoid hormones, which are widely used in the treatment of asthma, have been shown to potentiate physiological and biochemical beta-adrenergic responsiveness in asthmatics. These effects are presumably mediated through glucocorticoid receptors. In order to better understand glucocorticoid pharmacology in asthmatics, we assayed glucocorticoid receptors by directly binding a radioactively labelled glucocorticoid hormone, dexamethasone, to intact lymphocytes prepared from the peripheral blood of asthmatics and control subjects. Binding studies were performed with dexamethasone at 100 nM and 5 nM concentrations. At 100 nM dexamethasone, the mean number of lymphocyte glucocorticoid receptors (per cell) in control subjects (7191 +/- 385, n = 9) was not significantly different from that in asthmatic subjects (7772 +/- 437, n = 9). At 5 nM dexamethasone, the mean number of glucocorticoid receptors in control subjects (1177 +/- 194, n = 5) was not significantly different from that in asthmatic subjects (1215 +/- 108, n = 8). At 100 nM dexamethasone, males had significantly more receptors (7939 +/- 360, n = 11) than females (6764 +/- 72, n = 7). Our results suggest that the number of lymphocyte glucocorticoid receptors and the apparent affinity of dexamethasone for receptors are not related to the presence of severity of asthma; however, a significant sex effect exists which should be corrected for in future studies of lymphocyte glucocorticoid receptors.

Identification of calcium antagonist receptor binding sites using (3H)nitrendipine in bovine tracheal smooth muscle membranes

(3H)Nitrendipine binding to the bovine tracheal muscle membrane at 25 degrees C was rapid, saturable (Bmax = 14.8 +/- 3.9 fmol/mg protein) and of high affinity (Kd = 0.15 +/- 0.04 nM). The rank order of Ca2+ antagonists competing for airway (3H)nitrendipine binding was nitrendipine not equal to nisoldipine not equal to nifedipine much greater than verapamil. Cromolyn, however, neither inhibited nor increased the binding.

Effect of the serine-borate complex on the relative ability of leukotriene C4, D4 and E4 to inhibit lung and brain [3H] leukotriene D4 and [3H] leukotriene C4 binding: demonstration of the agonists' potency order for leukotriene D4 and leukotriene C4 receptors

To define the potency order of the leukotrienes for inhibition of [3H] leukotriene D4 and [3H] leukotriene C4 binding, we investigated leukotriene C4, D4 and E4 competition with and without the serine-borate complex in guinea pig lung and brain homogenates. Without it, the rank order of their potency for inhibition of lung [3H] leukotriene D4 or [3H] leukotriene C4 binding was leukotriene C4 = leukotriene D4 greater than leukotriene E4. Presence of the complex altered the potency order for both competition studies: for the [3H] leukotriene D4 competition it was leukotriene D4 greater than leukotriene E4 = leukotriene C4 and for the [3H] leukotriene C4 competition it was leukotriene C4 much greater than leukotriene D4 greater than or equal to leukotriene E4.

Genetic analysis of allergic disease in twins

One hundred seven pairs of twins, sixty-one MZT and forty-six DZT, were investigated for allergic disease by a questionnaire, reaginic antibody levels, bronchial reactivity to inhaled methacholine, and skin test responses. Intrapair correlation coefficients (ri) of measured clinical markers of atopy were determined and a heritability analysis was performed. The intrapair correlation coefficient for serum IgE was 0.82 for MZT and 0.52 for DZT. The methacholine area demonstrated greater correlation in MZT with an ri of 0.67 compared to 0.34 for DZT. The total ISTS had an intrapair correlation coefficient of 0.82 in MZT and 0.46 in DZT. Our analysis demonstrates that methacholine sensitivity, total serum IgE levels, and total skin test scores to be heritable traits and suggests a genetic contribution to their expression.

Identification of leukotriene D4 receptor binding sites in guinea pig lung homogenates using [3H]leukotriene D4

We have characterized [3H]leukotriene D4 binding to guinea pig lung homogenates. Both biphasic dissociation kinetics and curvilinear Scatchard plots indicated the presence of [3H]leukotriene high and low affinity states of the binding sites. The rank order of potency for the competition study was leukotriene C4 = leukotriene D4 greater than leukotriene E4 much greater than arachidonic acid, and for their contractile effect on lung strips was leukotriene C4 = leukotriene D4 = leukotriene E4 much greater than arachidonic acid. FPL-55712 was the only other agent tested that inhibited binding. These results suggest that binding of [3H]leukotriene D4 to the homogenate is consistent with its binding to specific leukotriene D4 receptor sites.

Protection by ipratropium bromide and metaproterenol against methacholine and histamine bronchoconstriction

To establish relative protection against methacholine and histamine, 40 micrograms of ipratropium bromide, an anticholinergic compound, 1.3 mg of metaproterenol or placebo aerosols were administered by metered-dose inhaler prior to inhalation challenge with methacholine or histamine in nine asthmatic subjects. Double-blind, randomized challenges were performed. Subjects required a mean methacholine dose of 1.72 +/- 0.73 and 2.46 +/- 0.72 (Ln inhalation units), and mean histamine dose of 2.16 +/- 0.65 and 2.68 +/- 0.49, to cause a drop of 20% and 35% respectively in the FEV1 following the placebo. In the methacholine challenges, both ipratropium bromide and metaproterenol had significant protection as compared to placebo (P less than 0.001). There was no statistical difference in the degree of protection against methacholine between ipratropium bromide and metaproterenol. In histamine challenges, metaproterenol had significant protection as compared to the placebo, while ipratropium bromide did not protect against histamine.

Methacholine inhalation and Gm allotypes in familial asthma

In this paper, we confirmed previous studies where the results showed an incomplete genetic predisposition to allergic asthma. Our results also showed that by using the degree of sensitivity to methacholine and Gm allotypes one can obtain a better characterization than presently available of individual susceptibility to asthma in a familial setting.

Decreased mononuclear cell beta-adrenergic receptors in bronchial asthma: parallel studies of lymphocyte and granulocyte desensitization

To assess the interaction of bronchial asthma and beta-agonist drugs, beta-adrenergic receptors were measured in human mixed leukocyte, mononuclear cell, and polymorphonuclear leukocyte cell membranes simultaneously. The densities and affinities of beta-adrenergic receptors were determined, by Scatchard analysis, with a potent beta-antagonist 125I-hydroxybenzylpindolol (125I-HYP) and compared among 12 nonatopic controls (group I), 13 mild asthmatics not taking drugs (group II), and eight asthmatics receiving long-term beta-agonist therapy (group III). Our findings were as follows. (1) Asthmatics not taking drugs (group II) have significantly lower mean mononuclear leukocyte beta-adrenergic receptor density (p less than 0.05) but no significant difference in mean polymorphonuclear leukocyte beta-adrenergic receptor density than the control group. (2) Asthmatics receiving long-term beta-agonist treatment (group III) had significantly lower mean beta-adrenergic receptor density in all three cell fractions (p less than 0.05). (3) Group I and II females had a higher mean beta-adrenergic receptor density in mixed leukocyte and polymorphonuclear cell fractions than males (p less than 0.05). (4) Terbutaline sulfate clearly caused desensitization of beta-adrenergic receptors in human leukocyte membranes in vivo. These results show that beta-adrenergic receptor density is influenced by cell type, beta-adrenergic agonist administration, and sex; they also show that bronchial asthma itself is associated with lower lymphocyte beta-receptor density.

Pharmacological characterization of effects of nifedipine on isolated guinea-pig and rat tracheal smooth muscle

Nifedipine, a relatively new Ca2+-channel blocking agent, has recently been shown to be effective in the treatment of exercise-induced asthma; however, the pharmacological mechanism by which it blocks bronchospasm is little understood. We have investigated and characterized its effects on the reactivity of isolated guinea-pig and rat tracheal smooth muscle. Although it (10(-8)--10(-7)M) blocked the contraction of the rat tracheal muscle to KCl and CaCl2, nifedipine (10(-7)--10(-6)M) did not significantly inhibit histamine, methacholine or serotonin-induced muscle contractions in guinea-pigs and the methacholine contraction in rats. Nifedipine produced a potent relaxation on contracted tracheal muscle. The concentration required to produce 50% relaxation on 10(-5)M histamine-precontracted guinea-pig tracheal muscle was 8.31 +/- 3.12 X 10(-9)M, and the extent of the nifedipine-induced relaxation could be modified by the baseline and active contracted tension. Nifedipine was more potent in producing the relaxation in guinea-pig tracheal muscle than isoproterenol, theophylline or verapamil. However, the time required for 50% relaxation by 3 X 10(-5)M isoproterenol was significantly less than the time for the nifedipine (3 X 10(-5)M) or verapamil (10(-4)M) effect. In addition, the Hill number of the nifedipine-induced relaxation was different from the value of the isoproterenol or verapamil effect. Our results indicate that nifedipine exerts a potent dilatory effect directly on airway muscle, and suggest that such effect could be one of its pharmacological actions on relieving bronchospasm.

Inhibitory effect of the CA2+ antagonist nifedipine on histamine release from rat peritoneal mast cells

45Ca uptake and histamine release was examined in mast cells from rats sensitized with ovalbumin and Bordetella Bertussis as an adjuvant. The uptake of 45Ca by the mast cells was significantly increased by stimulation with ovalbumin as was the release of histamine from the mast cells. Nifedipine, a calcium antagonist, inhibited the increase in both 45Ca uptake and histamine release stimulated by ovalbumin, though the effect on 45Ca uptake was stronger than that on histamine release.

GTP increases airway muscarinic antagonist binding sites: an effect regulated by Mg2+

Using [3H]QNB, we demonstrated that GTP and Gpp(NH)p increased muscarinic receptor high affinity sites in bovine tracheal muscle preparations; however, neither the dissociation constant of [3H]QNB binding sites nor pulmonary beta-adrenergic receptor sites was altered. The GTP effect on increasing the receptor sites was relatively small (16%), sensitive (ED50 0.48 microM) and specific (Gpp(NH)p greater than GTP = GDP greater than GMP much greater than ATP). Mg2+ potentiated this increase by up to 94.8%, whereas Na+, K+ and Ca2+ had no such effect.

Difference between lung and spleen susceptibility of beta-adrenergic receptors to desensitization by terbutaline

There are many reports about a marked down-regulation of beta-adrenergic receptors by beta agonists in human leukocytes. To determine whether beta receptors in lung tissue are down regulated by the long-term administration of beta agonists, as are those in the spleen (which consists largely of lymphocytes), we injected terbutaline (0.1 mg/kg, t.i.d.) intramuscularly into rats for either 3 or 6 days. We observed a significant decrease in beta-receptor density in spleen tissue but not in lung parenchyma, associated with terbutaline injection. The affinity for an antagonist did not change significantly in any group in either tissue. We did not observe any change in alpha 1-adrenergic receptors in the lung after this treatment. In in vitro studies, we also observed reduced beta-receptor density in spleen cells but not in lung parenchyma after incubation of these tissues with terbutaline. However, there was agonist-specific alteration in lung beta receptors. It was found that the isoproterenol competition curve for 3H-dihydroalprenolol binding shifted to the right and steepened, suggesting reduced affinity of the receptors for isoproterenol. We used whole lung and did not examine bronchial smooth muscle per se, nor were functional studies performed. Our results show a difference between lung parenchyma and spleen tissue in the susceptibility of beta receptors to desensitization by an adrenergic agonist and suggest that there may be such a difference in sensitivity between beta receptors in human lung and leukocytes.

Inhibitory effect of nifedipine and cromolyn sodium on skin reactions and 45Ca uptake and histamine release in rat mast cells induced by various stimulating agents

The effect of nifedipine, one of the calcium channel antagonists, was examined in allergic and nonspecific reactions using rat skin and peritoneal mast cells. Rat passive cutaneous anaphylaxis response mediated by IgE antibody was inhibited by nifedipine (100 micrograms/rat) and also by cromolyn sodium (5 mg/rat). Skin reactions induced by histamine or methacholine were not inhibited, and skin reaction induced by serotonin was slightly inhibited by these drugs. The 45Ca uptake and histamine release in sensitized mast cells stimulated by ovalbumin were suppressed by nifedipine. In actively sensitized cells, nifedipine seems to be more effective on the inhibition of 45Ca uptake, but less effective on histamine release than cromolyn sodium. In mast cells, nonimmunologically stimulated by concanavalin A, compound 48/80, and calcium ionophore A23187, nifedipine exerted considerable inhibitory effects on both 45Ca and histamine release.

Factorial rating system for comparative efficacy of antiasthmatic medication: a multicentric study report

Faced with 1-year daily medication diaries from over 300 patients, each documenting the use of from one to five medications a day, we found it was necessary to devise a system which would reduce this data into a form which would allow a meaningful interpretation of changes of medications in a single patient or group of patients. Since the medications were principally steroids, beta agonists, or xanthines, representative agents were chosen as the standard for each class and the other medications were rated against them. A conversion factor was then determined to allow comparison between classes. Each medication taken by a patient could now be expressed as a single number and the sum of all the medications would be the individual's Asthma Medication Index. The AMI allowed (i) evaluation of a single patient over time, (ii) comparison of different patients at any single point or over a period of time, and (iii) evaluation of entire groups of patients over time as was the case in our evaluation of Zaditen. Application of the system allowed the differentiation of two therapeutic agents versus placebo during a 1-year study, revealing excellent correlation with the physician's global assessment of the patient's improvement. With proper modification of the basic drug groups and intergroup factor relationship, the Index can be adapted to any disease state where a change in concomitant medication is an indicator of therapeutic effect.

Effect of BSA on Ca2+ influx in mast cells stimulated by ovalbumin

To examine the effect of bovine serum albumin (BSA) on the cell surface of mast cells, we measured 45Ca influx in mast cells from actively sensitized rats, and in cells passively sensitized in vitro with IgE-containing serum before or after BSA purification. Mast cells from actively sensitized rats showed a marked increase in 45Ca uptake after stimulation by ovalbumin. The uptake of 45Ca by mast cells passively sensitized before separation through BSA was also increased in response to ovalbumin. Variation in 45Ca uptake increased in the cells sensitized after separation. We did not observe a significant increase in 45Ca uptake in mast cells incubated with inactivated or normal serum compared to that of unstimulated cells.

Decreased sensitivity and response of isolated tracheal muscle to methacholine and histamine without changing the activity of pulmonary muscarinic receptors in the egg albumin-sensitized guinea pig

Guinea pigs were sensitized by daily intraperitoneal injections of 100 mg of egg albumin for 3 consecutive days and sacrificed at 30-35 days after the last injection. The in vitro sensitivity and response of the sensitized tracheal muscle to methacholine and histamine were significantly less than those of littermate controls. However, there was no difference between the dissociation constants and concentrations of pulmonary muscarinic receptor binding sites of the control and sensitized guinea pigs. We conclude that subsensitivity and hyporesponsiveness to methacholine and histamine occur in the airway muscle of this guinea pig model of experimental asthma and suggest that the decreased reactivity to methacholine might be due to defects beyond the receptor.

Comparison of muscarinic and beta adrenergic receptors between bovine peripheral lung and tracheal smooth muscles: a striking difference in the receptor concentration

This study was undertaken to compare the activity of muscarinic and beta adrenergic receptors in bovine peripheral lung to the corresponding receptor activity in tracheal smooth muscle. We used [3H] quinuclidinyl benzilate (QNB) and [3H]dihydroalprenolol (DHA) to measure muscarinic and beta receptor activity, respectively. Binding to QNB and DHA at 25 degrees C was rapid, reversible, saturable and of high affinity. The order of potency for cholinergic and adrenergic agents competing for binding was compatible with muscarinic and beta 2 adrenergic potencies. We found that the concentration of muscarinic receptor binding sites was 37-fold greater in the tracheal muscle preparation (2805 +/- 309 fmol/mg protein) than in the peripheral lung preparation (76 +/- 28 fmol/mg protein). Unlike muscarinic receptors, the lung contained 8-fold higher concentration of the beta adrenergic receptors than did the tracheal muscle (1588 +/- 417 vs. 199 +/- 42 fmol/mg protein). The dissociation constant or the agonist's inhibitory constant (Ki) for either receptor binding site, however, was not significantly different between the two tissues. Furthermore, in vitro contraction studies showed that the response of tracheal muscle strips to methacholine was markedly greater than the response of peripheral lung strips, a finding consistent with the QNB binding result. The muscle but not the peripheral lung strip exhibited a relaxing response to epinephrine. Our data indicate a striking quantitative difference in muscarinic and beta adrenergic receptors between lung tissue and tracheal muscle, and that each receptor in the lung is qualitatively similar to the corresponding receptor in the muscle.

Effects of chronic histamine and ovalbumin aerosols on pulmonary beta adrenergic receptors in sensitized guinea pigs

Using (3H) dihydroalprenolol, we demonstrated that the concentration of pulmonary beta adrenergic receptor binding sites was lower in guinea pigs showing a marked bronchoconstrictive response to histamine and in ovalbumin-treated guinea pigs. This result suggests that the changed concentration of the pulmonary beta receptors in an animal model of asthma could be resulted from bronchoconstriction stress.

Alpha and beta adrenergic receptors of canine lung tissue identification and characterization of alpha adrenergic receptors by two different ligands

Adrenergic receptors of canine peripheral lung tissues were measured by direct binding techniques using [3H]dihydroergocryptine ([3H]DHE), [3H]prazosin and [3H]dihydroalprenolol ([3H]DHA). All three ligands bound to canine lung tissue with saturability, stereospecificity and reversibility. Adrenergic agonists competed for binding of [3H]DHE and [3H]prazosin in the order: 1-epinephrine greater than 1-norepinephrine greater than d-epinephrine greater than d-norepinephrine greater than 1-isoproterenol. Adrenergic antagonists competed for binding of [3H]prazosin in the order: prazosin greater than phentolamine greater than yohimbine. Inhibition curves of [3H]DHE by prazosin or yohimbine were biphasic suggesting two subtypes of binding sites. Maximum binding capacities of [3H]DHE ranged from 30.6 to 42.7 fmol/mg protein. [3H]prazosin from 18.3 to 26.9 fmol/mg protein and [3H]DHA from 135.2 to 359.4 fmol/mg protein. When both [3H]DHE and [3H]prazosin were used in the same membrane preparation, specific binding of [3H]DHE was always more than that of [3H]prazosin. Since [3H]prazosin is considered to bind to alpha 1 adrenergic receptors specifically and [3H]DHE is considered to bind alpha 2 adrenergic receptors nonselectively, the difference between the numbers of the specific binding sites of these two ligands should represent alpha 2 adrenergic receptors. Alpha 2 adrenergic receptor density ranged from 9.5 to 21.1 fmol/mg protein. Our results suggest the existence of both alpha 1 and alpha 2 adrenergic receptors in canine peripheral lung tissue. Approximately 40% of alpha adrenergic receptors were alpha 2. The ratio of alpha/beta adrenergic receptors ranged from 1:3.3 to 1:10.4. The ratio of alpha 1/beta adrenergic receptors ranged from 1:6.7 to 1:21.1.

Protective effect opf lodoxamide tromethamine on allergen inhalation challenge

Lodoxamide tromethamine (U-42,585E) is a new drug intended for prophylaxis of mast cell-mediated allergic disease. It is a water-soluble, cromolyn-like agent with demonstrated activity in rat peritoneal mast cell assay, rat percutaneous anaphylaxis (rat PCA) and sensitized rhesus monkey airway system. Ten allergen-sensitive asthmatics were pretreated with lodoxamide (0.01, 0.1, or 1.0 mg) or placebo, then challenged with serial dilutions of allergen extract. Analysis of allergen dose-response curve parameters shows that pretreatment with lodoxamide offers significant protection against experimental allergen-induced bronchoconstriction. At 0.01 mg, lodoxamide was effective in over half the subjects tested. Administration of lodoxamide by inhalation at doses of 0.1 and 1.0 mg uniformly allowed subjects to tolerate significantly larger doses of inhaled allergen. Side effects observed at these doses were minimal.

Nonantibiotic effects of macrolide antibiotics of the oleandomycin-erythromycin group with special reference to their "steroid-sparing" effects

Certain macrolide antibiotics, such as troleandomycin (TAO), oleandomycin, and erythromycin estolate (Ilosone), can lower the maintenance dose of glucocorticoids required by severely asthmatic patients. These effects were postulated to be caused by an as yet undefined steroid-sparing effect. In this study, TAO in combination with methylprednisolone, when compared with methylprednisolone alone, was demonstrated to significantly increase liver glycogen deposition in adrenalectomized mice, intact mice, and adrenalectomized rats; protect histamine-sensitized mice following beta adrenergic blockade or adrenalectomy; further decrease the steroid-lowered glucose tolerance of mice and significantly increase the plasma corticosteroid levels in rats. TAO alone did not have these effects. TAO plus betamethasone, and erythromycin estolate plus methylprednisolone also increased liver glycogen deposition. However, TAO did not appear to potentiate the effects of hydrocortisone. Erythromycin stearate and to a lesser degree erythromycin ethylsuccinate when combined with methylprednisolone also decreased histamine lethality in mice. Leucomycin and tetracycline did not enhance the effects of methylprednisolone. TAO, alone or with methylprednisolone, did not alter serum glutamic oxaloacetic transaminase (SGOT) levels in rats. Thus, TAO and some other macrolides did not exert their effects on corticosteroids as antimicrobial agents, adrenocorticotropic hormone (ACTH)--like compounds, or quasisteroids, but as steroid-sparing agents by some undefined mechanism.

A comparison of the beta-blocking activities of practolol, sotalol, and propranolol in human and guinea pig tracheal smooth muscle

Beta adrenergic blockade was studied in vitro with human tracheal muscle strips and guinea pig tracheal chains. It was shown in isolated smooth muscle from both man and guinea pig that the order of potency for the three beta-blocking agents studied was: propranolol greater than sotalol greater than practolol. Under the conditions of this study, propranolol was about 30,000 times and sotalol about 30 times as potent as practolol. The order of potency suggests that the nature of adrenergic blockade induced by practolol on tracheal smooth muscle is only weakly beta2-relative to the blocking effects of propranolol and sotalol. Beta adrenergic blockade by propranolol, sotalol, and practolol produced different degrees of increased histamine lethality in mice. Whereas both propranolol at 0.01 mg/kg and sotalol at 1.0 mg/kg resulted in 100% histamine-induced lethality, practolol at 50 mg/kg resulted in only 50% histamine-induced lethality. These data, when added to those from our previous studies, suggest that the mechanisms responsible for resistance to the effects of histamine in untreated mice are at least partially mediated by the beta2-adrenergic system. Thus, in three different tissues, the blocking activity of practolol was shown to be less than that of sotalol or propranolol.

Cromolyn therapy in patients with bronchial asthma. Effect on inhalation challenge with allergen, histamine, and methacholine

The action mechanism of cromolyn sodium and its effect on bronchial sensitivity to allergen, methacholine chloride, and histamine inhalations were studied in 17 asthmatic subjects. Cromolyn capsules or placebo was administered by an inhaler (Spinhaler) randomly on alternate days 30 minutes before aerosol challenge. Cromolyn and placebo did not differ in their effect on bronchial response to histamine or methacholine. However, the degree of decrease in forced vital capacity and forced expiratory volume in one second after allergen challenge was significantly reduced by cromolyn in 15 of 17 subjects. Immediate and delayed reactions of itching, tightness, or wheezing developed in 14 subjects after allergen challenges following placebo intake and were prevented or substantially inhibited by cromolyn.

The effect of pertussis and beta adrenergic-blocking agents on mast cells

Pertussis vaccine injected ip in doses known to cause hypersensitization resulted in a marked decrease in the number of mast cells from the peritoneal washings of rats and mice. A significant reduction was obtained as early as one day after pertussis injection of ten billion cells in rats and was marked after 5 to 7 days. A maximum reduction in the number of mast cells was obtained by a dose of 20 billion cells. There was no detectable histamine biological activity in the supernatant from peritoneal washings obtained after 10 min, 60 min, and 24 hr from control and pertussis-treated rats, indicating that pertussis did not cause degranulation of mast cells in vivo. The histamine content in the precipitated mast cell pellets from control rats was much higher than the corresponding histamine content from pertussis-treated rats. In rats and mice, propranolol and other beta adrenergic-blocking agents caused degranulation of mast cells in the peritoneal washings in vitro. Practolol was the least effective beta adrenergic-blocking agent in degranulating mast cells. Catecholamines, histamine, 6-hydroxydopamine, methacholine, and pertussis failed to cause any degranulation. Isoproterenol protected the mast cell against the degranulation induced by propranolol. Propranolol caused bluing in rat and mice skin when injected id. Mast cells from control and pertussis-injected rats were equally sensitive to propranolol in vitro. The low recovery of mast cells from the peritoneal washings of rats and mice is thought to be due to mobilization of mast cells away from the peritoneum.

Bronchial reactivity to histamine before and after sodium cromoglycate in bronchial asthma

Out of 19 patients with extrinsic bronchial asthma challenged with 123 mug histamine acid phosphate by intravenous infusion only 13 responded with a fall in FEV1 of over 10% (mean 16%). Seventeen of these patients were given histamine 2 mg/ml by aerosol, and all responded with a mean decrease in FEV1 of 37.8%. When challenged with allergen extract by aerosol the mean decrease in FEV1 was 37.5%. After 40 mg sodium cromoglycate 15 of the 17 patients showed significant protection against allergen challenge with a mean decrease in FEV1 of only 23.6%. Inhalation of 40 mg sodium cromoglycate, however, failed to protect against histamine given by either the intravenous or aerosol route. Histamine given intravenously to asthmatic patients produces less of a bronchial response than when given by aerosol, even though the intravenous route produces many more systemic symptoms, such as flushing and throbbing headache. The protection of sodium cromoglycate against an allergen inhalation challenge is not due to histamine antagonsim.

Comparison of the bronchodilating effects of SCH 1000 with isoproterenol in patients with bronchial asthma

The effect of SCH 1000 and isoproterenol was evaluated in 10 patients with extrinsic asthma. The onset of action for the SCH 1000 dose compared to the baseline response occurred at or before 15 minutes (FEV1 and MEFR). The onset of action for the isoproterenol dose occurred at or before one minute for all three pulmonary function variables. At the 1-, 3-, 6- and 15-minute intervals the response to the isoproterenol dose was significantly greater than the response to the SCH 1000 dose for FEV1, FVC and MEFR. At 30 and 60 minutes, however, the response to SCH 1000 was progressively increasing, whereas the response to isoproterenol was decreasing. The maximum improvement in FEV1 for isoproterenol was 49% at three and six minutes, whereas for SCH 1000 was 28% at 60 minutes. In patients with chronic bronchitis or bronchial asthma SCH 1000 may be considered as a therapeutic alternative to beta-adrenergic bronchodilators and in patients who also have cardiac arrythmias or angina pectoris and are adversely affected by sympathomimetic drugs.

The effect of beta adrenergic blockade on bronchial sensitivity to acetyl-beta-methacholine in normal and allergic rhinitis subjects

The effect of propranolol inhalation on sensitivity to methacholine inhalation was studied in normal and allergic rhinitis subjects to determine whether beta adrenergic blockade alters sensitivity to mediators in nonasthmatic atopic individuals. A partial beta adrenergic blockade is suggested as being instrumental in asthma. Hay fever patients studied showed similar effects and also developed asthma for the first time.

Comparison of respiratory and cardiovascular effects of isoproterenol, propranolol, and practolol in asthmatic and normal subjects

Pulmonary functions, by means of FEV1, FVC, and airway resistance, and cardiovascular responses, i.e., ECG, blood pressure, and pulse contour, were measured in 10 control and 15 symptom-free asthmatic subjects during and after the infusions of isoproterenol, with or without previous administration of propranolol or practolol. Bronchial sensitivity to methacholine and response to isoproterenol after methacholine were also measured. Bronchial sensitivity to methacholine challenge was markedly enhanced by propranolol and the effect of isoproterenol infusion on the pulmonary function was also significantly diminished, whereas practolol did not reveal any effect on bronchial sensitivity to methacholine or isoproterenol. The above changes were much more profound in symptom-free asthmatic subjects than in control subjects. The results suggest that practolol does not significantly affect the beta-2 bronchial receptors, is safe to use in asthmatic subjects, and is consistent with an abnormality of these receptors in bronchial asthma.

Bronchial sensitivity to methacholine in current and former asthmatic and allergic rhinitis patients and control subjects

Ninety-eight subjects underwent methacholine (Mecholyl) aerosol challenge at a concentration of 5 mg/ml. All atopic groups differed significantly in their bronchial response to Mecholyl compared to nonatopic control subjects. Nineteen normal subjects had a mean decrease of 11.4% in forced expiratory volume in one second (FEV1) with 128 Mecholyl inhalations and 2 decreased by greater than 20%. Fifteen of 27 allergic rhinitis patients had a positive response to Mecholyl as defined by a decrease in FEV1 greater than 20%. Four of these responders developed greater diminution in FEV1 response with additional Mecholyl inhalations in a manner similar to that seen in the asthmatic patients. Eighteen current asthmatics showed the greatest bronchial sensitivity to Mecholyl with a mean 33% decrease in FEV1 at 4.5 inhalations. One hundred per cent of current asthmatics and 82% (28 of 34) of former asthmatics (free of asthma symptoms for 1 to 20 yr) showed positive response to Mecholyl. A 20% decrease in FEV1 with a total of 20 inhalations or less is consistent with a diagnosis of "current asthma," and even 20 of 34 former asthmatics responded in this manner. The Mecholyl aerosol test can be used to diagnose previous and current asthma and may be of value in predicting asthma in hay fever patients.