Selective breeding of two lines of guinea pigs differing in bronchial sensitivity to acetylcholine and histamine exposure

We developed two lines of guinea pigs, one as model animals for bronchial asthma with bronchial hypersensitivity and the other with hyposensitivity as a control. In the last four years, the bronchial hypersensitive line (BHS) and hyposensitive line (BHR), both derived from Hartley strain guinea pigs, have been selected by using bronchial reactivity to acetylcholine and to histamine as parameters. Both lines have reached the F6 generation. The following results were obtained with the two lines: 1) Sib and cous in matings, and mating of selected consanguineous individuals were adopted in breeding BHS and BHR. The breeding started with six families, each, but in the F6 generation the number of families decreased to two in each line. 2) Appearance rates of hyper- or hyposensitivity to acetylcholine and histamine increased with successive generations in both lines, which had been completely separated by the F6 generation. 3) Coefficients of inbreeding in BHS and BHR in the F6 generation ranged from 42% to 45% in the former and 42% in the latter. 4) Heritabilities (h2) of BHS and BHR for the appearance rates of sensitivity to acetylcholine were presumed to be 0.54 in the former and 0.69 in the latter. 5) No difference in the body weight of 0, 20, and 40 day-old BHS was observed in any generation. On the other hand, the body weight of 20 and 40 day-old BHR tended to decrease with successive generations. 6) Mean litter sizes of BHS and BHR in each of the generations ranged from 2.24 to 3.47 animals in the former and from 2.63 to 3.38 animals in the latter.(ABSTRACT TRUNCATED AT 250 WORDS)     

Characteristics of two lines of guinea pigs (BHS and BHR) differing in bronchial sensitivity to acetylcholine and histamine exposure.

In a previous study, we reported that as model animals to be used in the study of bronchial asthma in humans, two lines of guinea pigs were developed by ourselves: bronchial hypersensitive line (BHS) and bronchial hyposensitive line (BHR) as a control. Studies on biological characteristics in guinea pigs of two lines were undertaken, and the following results were obtained. 1) Airway resistance of guinea pigs of the two lines to intravenously administered acetylcholine, histamine and leukotriene D4 was found to be different between BHS and BHR. Airway resistance of BHS to the chemicals was increased compared with those of BHR. 2) The number of muscarinic acetylcholine receptors in lung membrane preparation and its affinity increased significantly in BHS compared with those of BHR. In beta-adrenergic and histamine H1 receptors, there was observed no difference between BHS and BHR. 3) No difference in IgE antibody production to ovalbumin was observed between BHS and BHR. 4) When total leukocytes and differential leukocyte count (percentage, %) in peripheral blood of BHS and BHR were examined, relative percentage of lymphocytes and eosinophils was significantly higher in BHS than in BHR, while percentage of neutrophils was significantly lower in the former than in the latter.     

Tropical Malaysians and temperate Koreans exhibit significant differences in sweating sensitivity in response to iontophoretically administered acetylcholine

Natives of the tropics are able to tolerate high ambient temperatures. This results from their long-term residence in hot and often humid tropical climates. This study was designed to compare the peripheral mechanisms of thermal sweating in tropical natives with that of their temperate counterparts. Fifty-five healthy male subjects including 20 native Koreans who live in the temperate Korean climate (Temperate-N) and 35 native tropical Malaysian men that have lived all of their lives in Malaysia (Tropical-N) were enrolled in this study after providing written informed consent to participate. Quantitative sudomotor axon reflex testing after iontophoresis (2 mA for 5 min) with 10% acetylcholine (ACh) was used to determine directly activated (DIR) and axon reflex-mediated (AXR) sweating during ACh iontophoresis. The sweat rate, activated sweat gland density, sweat gland output per single gland activated, and oral and skin temperature changes were measured. The sweat onset time of AXR (nicotinic-receptor-mediated) was 56 s shorter in the Temperate-N than in the Tropical-N subjects (P < 0.0001). The nicotinic-receptor-mediated sweating activity AXR (1), and the muscarinic-receptor-mediated sweating activity DIR, in terms of sweat volume, were 103% and 59% higher in the Temperate-N compared to the Tropical-N subjects (P < 0.0001). The Temperate-N group also had a 17.8% (P < 0.0001) higher active sweat gland density, 35.4% higher sweat output per gland, 0.24°C higher resting oral temperature, and 0.62°C higher resting forearm skin temperature compared to the Tropical-N subjects (P < 0.01). ACh iontophoresis did not influence oral temperature, but increased skin temperature near where the ACh was administered, in both groups. These results suggest that suppressed thermal sweating in the Tropical-N subjects was, at least in part, due to suppressed sweat gland sensitivity to ACh through both recruitment of active sweat glands and the sweat gland output per each gland. This physiological trait guarantees a more economical use of body fluids, thus ensuring more efficient protection against heat stress.     

Bronchial reactivities in guinea pigs to acetylcholine or histamine exposure

The bronchial reactivities in Hartley guinea pigs to acetylcholine (ACh) or histamine (Hist) were investigated, and the following results obtained; 1. Eight-week-old animals were exposed to ACh and Hist. A significant relationship was observed between the concentrations of the chemicals and the time needed to produce falling down (TNPFD) due to the asthmatic reaction to ACh and Hist. 2. Eight-week-old animals were exposed to 0.1% ACh and 0.05% Hist, for which the mean TNPFD +/- standard error were 377 +/- 33 sec and 122 +/- 5 sec respectivity. However, no difference in reactivity between male and female animals was noted. 3. Eight- and 9-week-old animals were exposed to 0.01% ACh and 0.025% Hist. A positive correlation was observed (r = 0.736, p less than 0.01) between the TNPFD for ACh and that for Hist. 4. Growing animals from 2 weeks to 20 weeks old were exposed to 0.08% ACh and 0.025% Hist. After inhalation of both chemicals, 6-week-old animals showed the greatest prolongation of mean TNPFD (lowest sensitivity). 5. Eight-week-old animals were exposed to 0.08% ACh and 0.025% Hist. With both of these chemicals, a positive correlation was observed between TNPFD and dose threshold (ACh r = 0.886, p less than 0.001; Hist r = 0.891, p less than 0.001).     

Strain differences in susceptibility to experimental allergic encephalomyelitis and the immune response to the encephalitogenic determinant in inbred guinea pigs.

Strain differences in susceptibility to experimental allergic encephalomyelitis (EAE) in guinea pigs were correlated with the cellular immune response to the basic encephalitogenic protein (BE). The response to BE was determined in strains 2 and 13 guinea pigs in vivo by the delayed hypersensitivity skin test and in vitro by the lymphocyte transformation technique. The response to the intact BE of both heterologous (bovine) and homologous (guinea pig) origins was indistinguishable between the two strains. Guinea pigs sensitized with the guinea pig BE showed complete cross-reaction when tested with the bovine BE. On the other hand, there appears to be significant differences in the response to specific determinants on the molecule. Thus, only strain 13 and F₁ hybrids which are susceptible to EAE responded to the encephalitogenic nonapeptide (residue 114–122 of the BE molecule), whereas strain 2 guinea pigs which are resistant to EAE did not respond to this determinant.     

Individual differences in sensitivity to bitter-tasting substances

Perception of several bitter-tasting compounds was tested in52 subjects. Stable individual differences in the perceivedintensity of the bitterness of suprathreshold concentrationsof quinine sulfate (QSO₄) and urea were found. Whereas 18 subjectsjudged selected concentrations of these compounds to be equallybitter, 17 found QSO₄ to be more bitter than urea, and 17 foundurea to be more bitter than QSO₄. These reliable individualdifferences were significantly related to threshold sensitivityto QSO₄; that is, individuals who perceived QSO₄ to be moreintense than urea at suprathreshold concentrations also hadlower QSO₄ thresholds than did those who perceived urea to bemore intense than QSO₄. There appeared to be no relationshipbetween the relative perceived intensities of these compoundsand rating of the bitterness of PROP (6-n-propylthiouracil).However, QSO₄-sensitive individuals tended to find the bitternessof suprathreshold caffeine and sucrose octaacetate to be greaterthan that of suprathreshold magnesium sulfate, whereas the reversewas true for urea-sensitive individuals. This pattern parallelsthe pattern of cross-adaptation among these compounds reportedby other investigators. These results are consistent with theexistence of multiple bitter transduction sequences and suggestthat individual differences in response to various bitter compoundsmay reflect differences in teh relative availability of specifictransduction sequences.     

Lysophosphatidic acid enhances airway response to acetylcholine in guinea pigs.

Inhalation of lysophosphatidic acid (LPA, 1-100 microg/ml) for 2 min enhanced the airway response induced by intravenous injection of ACh in guinea pigs. At 30 min after inhalation of LPA, the airway response to ACh was two fold higher than that before inhalation. This enhancement of airway response to ACh was partially inhibited by capsaicin desensitization or bilateral vagotomy. These results suggested that the enhancement of airway response to ACh induced by LPA may be due to the activation of capsaicin-sensitive fibers. It can be also contribute to bronchial asthma or other types of pulmonary disease such as cough variant asthma and atopic cough.     

Individual differences in sensitivity and tolerance to alcohol

Abstract

Human responses to alcohol—especially sensitivity and acute behavioral tolerance—are being studied within a behavioral genetic design involving comparisons of scores from monozygotic twins, dizygotic twins, nontwin siblings, and unrelated (adoptee) pairs reared in the same family from infancy. The planned genetic analyses must await completion of data collection. The present sample is, however, adequate for analyses of means and for some analyses of individual differences in responses. For most of the measures being used, we find the usual mean decrement in performance after alcohol dosing to 0.100 BAC, but individual differences in response to alcohol are large, and a few individuals actually improve in performance after dosing. Also, on two tests, Cancellation and Block Rotations, there is a significant mean improvement in performance immediately after dosing. As yet we do not have a satisfactory explanation for this phenomenon. On most but not all of the tests, performance improves after the initial decrement during a 3‐hour period in which blood alcohol levels are maintained by additional hourly doses. This improvement may be due in part to practice effects, as well as to the development of acute behavioral tolerance to ethanol (ABTE). We are still exploring ways in which these effects may be disentangled, using data from concurrent placebo control subjects and from pre‐dosing test sessions. It is already apparent, nevertheless, that most of the variability in sensitivity and ABTE is related to pre‐existing individual variability rather than to gender, age, height, weight, or drinking history. By mailing annual questionnaires to all participants, we hope to be able to test the hypothesis that those who were relatively insensitive to ethanol or who showed a relatively large amount of ABTE during the test sessions may be at increased risk for heavy alcohol consumption.     

Effect of hydrogen peroxide on neuron sensitivity to acetylcholine

The dose-dependent effect of hydrogen peroxide on snail neuromembrane chemosensitivity was studied by means of standard voltage-clamp method. Short-term exposure (7 min) of neurons to H(2)O(2) (10(-11)-10(-4) M) caused dose-dependent depression of Acetylcholine (Ach)-induced ionic currents in the membrane. The H(2)O(2)-induced depression of Ach-sensitivity of membrane was more pronounced in K(+)-free solution than in normal physiological solution and it disappeared in cold medium (5 degrees C). The H(2)O(2) (10(-11)-10(-4) M) decreased membrane electrical conductivity and cell volume. The dose-dependent decrease in Ach-sensitivity of the snail neuromembrane by H(2)O(2) may be due to a decrease in the number of functionally active membrane receptors caused by a decrease in membrane active surface. H(2)O(2)-induced decrease in Ach-sensitivity has a metabolic but Na(+)-K(+) pump independent character, the nature of which is the subject for current investigation.     

The role of intracellular processes in regulating neuronal sensitivity to acetylcholine

Intracellular regulatory mechanisms of neuronal response to acetylcholine were studied on intracellularly perfused isolated neurones of Lymnaea stagnalis using voltage-clamp technique. It was found that at the change of concentration of free intracellular Ca2+ from 0.06 to 0.7 microM the inhibitory effect of intracellularly added serotonin depends on Ca2+, and the modulation of acetylcholine responses by intracellular serotonin is unchanged. The blockers of calmoduline trifluoperazine and W-7 inhibit inward acetylcholine current at both intra- and extracellular introduction. Possible mechanisms mediating the effect of intracellularly added serotonin on the membrane cholinoreceptors of neurones are discussed.     

'Wanted-standard guinea pigs': standardisation and the experimental animal market in Britain ca. 1919-1947

In 1942 a coalition of twenty scientific societies formed the Conference on the Supply of Experimental Animals (CSEA) in an attempt to pressure the Medical Research Council to accept responsibility for the provision of standardised experimental animals in Britain. The practice of animal experimentation was subject to State regulation under the Cruelty to Animals Act of 1876, but no provision existed for the provision of animals for experimental use. Consequently, day-to-day laboratory work was reliant on a commercial small animal market which had emerged to sustain the hobby of animal fancying. This paper explores how difficulties encountered in experimental practice within the laboratory led to the problematisation of biomedical science's reliance upon a commercial market for animals during the inter-war period. This is shown to have produced a crisis within animal reliant experimental science in the early 1940s which enabled the left-wing Association of Scientific Workers to cast science's reliance on a free market as economically inefficient and a threat to the reliability of British research. It is argued that the development of standard experimental animals in Britain was, therefore, embedded within the wider cultural, societal, political and economic national context of the time.     

Strain differences of the ability to hydroxylate methotrexate in rats

Converting activity of methotrexate (MTX) to 7-hydroxymethotrexate (7-OH-MTX) was examined using eight strains of rats. Marked variability of the activity was found in liver cytosols from the rats. The highest activity was observed with Sea:SD rats, followed by LEW/Sea and Jcl:Wistar rats. The lowest activity was observed with WKA/Sea rats. The difference in the activity between Sea:SD and WKA/Sea strains was 104-fold. The variation was correlated to the strain difference of benzaldehyde oxidase activity in the rats. The cytosolic 7-hydroxylase activities in other tissues of Sea:SD rats were much higher than those of WKA/Sea, similarly to the case in liver. The liver microsomes of Sea:SD rats exhibited no 7-hydroxylase activity toward MTX even in the presence of NADPH. The cytosolic 7-hydroxylating activity of the livers of Sea:SD rats was inhibited by menadione, β-estradiol, chlorpromazine and disulfiram, inhibitors of aldehyde oxidase, but not oxypurinol, an inhibitor of xanthine oxidase. The purified aldehyde oxidase from the livers of Sea:SD rats exhibited a significant 7-hydroxylating activity toward MTX. However, xanthine oxidase had no ability to hydroxylate MTX. These facts suggest that MTX hydroxylating activity in rats is predominantly due to aldehyde oxidase, and the strain differences are due to the variations of the flavoenzyme level.     

Intraspecific differences in Cucumis sativus sensitivity to ultraviolet-B radiation

Cucumber ( Cucumis sativus L.) cultivars Marketmore, Lama, XPH 1187, XPH 1484 and Sprint 440 (N) were grown in a greenhouse under two levels of biologically effective ultraviolet-B ( UV -B) radiation (daily dose: 0 and 11.6 kJ m⁻² UV-B_BE) for 31 days. Significant intraspecific differences were observed in plant height, number of leaves, leaf area and total dry weight. Based upon total biomass accumulation, Marketmore was found to be the most tolerant, and XPH 1484 the most sensitive to UV-B radiation. The dose response of accumulation of UV absorbing compounds (measured as absorbance of methanolic extracts) in leaf tissues showed an increase in UV absorbing compounds with UV-B dose in Marketmore, Sprint 440 (N) and XPH 1187. In Lama and XPH 1484, however, doses below 8.7 kJ m⁻² UV-B_BE produced no change in UV absorbing compounds. This study suggests that intraspecific differences in UV-B radiation sensitivity in cucumber may be related to inherent differences in the accumulation of UV absorbing compounds in leaves.