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Biomedical subjects

L DeRoth

Publications and source records attributed to L DeRoth.

At least 19 recordsLinked to original sources
PubMed1997

Modulation of the effects of norepinephrine uptake inhibitors on the norepinephrine-induced contractile response of the porcine uterine artery during early pregnancy.

The effects of norepinephrine (NE) uptake inhibitors on the porcine uterine artery's contractile response to NE and their potential alteration during early pregnancy (Day 13 postcoitus; day of coitus = Day 0) in comparison with the end of the luteal phase (Days 11-14; first day of behavioral estrus = Day 0) was investigated. This pregnancy time point is characterized by a transient increase in resting uterine blood flow dependent on the presence of blastocysts, an increased endometrial vascular permeability, and the beginning of the endometrial attachment of the blastocysts. A cumulative concentration-response curve (CCRC) to NE was produced in isometrically-mounted rings. Cocaine (5 microM) was used to inhibit neuronal NE uptake and hydrocortisone (30 microM) was used to inhibit extraneuronal NE uptake. Either drug alone induced a leftward shift of the CCRC to NE without affecting the maximal response. This shift had the same amplitude at the end of the luteal phase and in early pregnancy. However, the leftward shift induced by cocaine was larger than that induced by hydrocortisone only in early pregnancy, and the leftward shift induced by exposure to both hydrocortisone and cocaine was larger in early pregnancy than at the end of the luteal phase. These results suggest that a significant sensitization of the contractile response of the porcine uterine artery to NE is induced by neuronal and extraneuronal uptake inhibitors and that this effect is altered in early pregnancy, possibly reflecting the existence of a mechanism protecting the uterine artery against excessive sympathetic stimulation.

Animals↗
PubMed1990

Erythrocyte osmotic fragility, serum creatine kinase and its isoenzymes related to body weight in porcine malignant hyperthermia.

Erythrocyte osmotic fragility, serum creatine kinase (CK) and its isoenzymes (CK-MM, CK-MB and CK-BB) were determined in pigs susceptible (SMH) and resistant (RMH) to malignant hyperthermia at three different body weights (Group 1, 10 to 25 kg; Group 2, 26 to 55 kg; Group 3, 56 to 95 kg). The halothane challenge test was used for determining susceptibility to malignant hyperthermia (MH). Significantly (P less than 0.05) greater erythrocyte haemolysis at saline concentrations of 80 to 100 mM NaCl occurred only between SMH and RMH pigs for body weight group 2. The determination of blood enzyme activities revealed also a significant (P less than 0.001) increase for total CK, CK-MM and CK-BB in SMH and RMH pigs of body weight Group 2. Furthermore in SMH pigs, total CK, CK-MM and CK-MB activities were significantly (P less than 0.05) greater in the animals of body weight Group 2. It was concluded that, in SMH pigs, weighing between 26 and 55 kg, there is a relationship between erythrocyte osmotic fragility, plasma CK, CK isoenzyme activities and muscle development.

Animals↗
PubMed1990

Prediction of the halothane (Hal) genotypes by means of linked marker loci (Phi, Po2, Pgd) in Quebec Landrace pigs.

Quebec Landrace pigs (n = 896) were halothane tested and blood samples were taken for the determination of Phi, Po2 and Pgd phenotypes. The incidence of the halothane positive pigs was 5.3%. The frequencies of the favorable alleles PhiA, Po2S and PdgA were respectively 29.2%, 39.6% and 64.4%. The highest linkage disequilibrium was found between Hal-Phi (0.0606) followed by Hal-Pgd (0.0428) and Hal-Po2 (-0.0308). Alleles PhiB, PgdB and Po2F were associated respectively with 97%, 81% and 74% of Haln haplotypes. It was concluded that a selection in order to increase the favorable marker loci PhiA and PgdA would reduce the Haln frequency in Quebec Landrace pigs.

Alleles↗
PubMed1989

Effects of exercise on skeletal muscle and serum enzyme activities in pigs.

In order to determine skeletal muscle and serum enzyme activities following exercise, six adult Landrace pigs were submitted to 10 min running on a treadmill (0.5 m/s, on a 12% gradient) and compared to six controls. Blood samples were obtained just before the exercise, immediately after, and 24 h, 48 h and 144 h after exercise. Muscle biopsies were taken from the longissimus dorsi and biceps femoris 24 h after exercise. Total lactic dehydrogenase (LDH) and LDH isoenzymes in muscle and serum were unchanged. In muscle homogenates, there was no difference in total creatine phosphokinase (CK) activity between the two groups. Total CK activity in the biceps femoris muscle represented only 59% of that observed in the longissimus dorsi muscle. A mean CK-MB value of 2.5% was found in the control group for both muscles but after exercise it was 9.5% (p less than 0.05) for the biceps femoris and 12.2% (p less than 0.01) for the longissimus dorsi muscle. In serum, the total CK (p less than 0.05), CK-MM (p less than 0.05) and CK-BB (p less than 0.05) increased immediately after the exercise, followed by a progressive decrease.

Animals↗
PubMed1988

Pharmacologic relevance of dihydropyridine binding sites in membranes from rat aorta: kinetic and equilibrium studies.

The kinetic features of the interaction of dihydropyridines with rat aortic smooth muscle were investigated in parallel mechanical and binding studies. The inhibitory action of (+)-PN200-110 and nisoldipine on contractions evoked by potassium chloride depolarization was characterized by a pronounced time dependency, in which the inhibition increased slowly after depolarization to attain a steady-state value, while with (-)-PN200-110 and (+)-Bay K8644 the inhibition was almost instantaneous. To explain these observations, specific binding sites for dihydropyridines were studied in membranes isolated from rat aorta, using [3H](+)-PN200-110 as a radioligand. We found that the time course of the development of inhibition of potassium chloride-evoked contractions by various concentrations of (+)-PN200-110 paralleled the time course of [3H](+)-PN200-110 binding to isolated membranes and that the level of inhibition was predictable from the level of occupation of these binding sites. These results indicate that depolarization increases the affinity of calcium channels for dihydropyridines in vascular smooth muscle and that the time course of the inhibitory effect on contraction is determined by the time course of association with the high-affinity state of the channel.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1988

Halothane induced vasomotion of coronary, renal and iliac arterial rings in malignant hyperthermia susceptible swine.

Animals were identified as porcine malignant hyperthermia susceptible by halothane testing and were slaughtered at 90 kg of body weight. Coronary, renal and iliac arteries were isolated, dissected and 5 mm rings were mounted in 20 mL organ baths with modified Krebs solution maintained at 37 degrees C and oxygenated with 95% O2, 5% CO2. Halothane at 0%, 0.5%, 2% and 5% concentration was bubbled in the organ baths and mechanical responses were recorded over a period of 25 min. Halothane free arteries remained quiescent and the arteries from the halothane sensitive and from the halothane resistant groups reacted similarly. All arteries in the presence of halothane responded with an initial contraction of short duration followed by a relaxation and both phenomena occurred in a concentration-dependent fashion. The iliac artery was the most sensitive to halothane and responded to 0.5% concentration while coronary and renal arteries maintained the resting tension of 4 g. These results demonstrate that vascular smooth muscle, like skeletal muscle and unlike respiratory smooth muscle, has a direct pharmacological response to halothane. These observations led to the postulate that halothane by its transient but significant vasoconstrictive action could be a contributing factor to initiate the fulminant reactions occurring in malignant hyperthermia.

Animals↗
PubMed1986

Effects of bolus injection of epinephrine and norepinephrine on systolic time intervals in stress-resistant and stress-susceptible pigs.

Systolic time intervals were measured in 15 stress-susceptible (SS) pigs to derive regression equations to determine to what extent their ventricular functions differed from those of stress-resistant (SR) pigs. Regression analysis revealed that the RR interval was the variable that was significantly (P less than 0.01) related to electromechanical systole and left ventricular ejection time. The preejection period (PEP) was independent of the RR interval. A normal increase of all systolic time intervals with age, independent of the RR interval, was also observed in SR and SS pigs. The 55-kg SS pigs had a higher noradrenergic tone than did 15-kg and 90-kg SS pigs, because their mean arterial blood pressure was higher and because their index values for electromechanical systole and their PEP were shorter than those of SR pigs of the same body weights. The cardiovascular responses to biogenic amines were also different according to the degree of development and stress susceptibility. Changes in mean arterial pressure and PEP were not as pronounced after injections of epinephrine and norepinephrine (10(-8) mol/kg of body weight) were given. Subsequently, a decrease in cardiovascular responses to epinephrine and norepinephrine injections in 90-kg SS pigs were recorded. These results indicate that 55-kg SS pigs have a higher level of circulating catecholamines and that the myocardium becomes less sensitive to epinephrine and norepinephrine after it is chronically exposed to these amines.

Animals↗
PubMed1986

Physiological responses to treadmill exercise and ambient temperature in normal and malignant hyperthermia susceptible pigs.

Ten susceptible and ten resistant pigs to malignant hyperthermia were used to observe the effects of exercise and ambient temperature on selected physiological parameters. Pigs were submitted to a ten minute exercise on a treadmill operating at a speed of 1.8 km/h and inclined to 11 degrees. Exercise in the first group was at an ambient temperature of 14 degrees C, and in the second at 29 degrees C. The right carotid artery was previously cannulated for blood pressure measurements and for repeated blood sampling during exercise. Arterial pressure, heart rate, rectal and cutaneous temperatures were recorded. Levels of cortisol, creatine kinase and its isoenzymes were measured. At 14 degrees C, exercise caused some physiological adjustments in susceptible animals; heart rate, skin temperature and cortisol levels increased (P less than 0.05). In resistant pigs, only the heart rate was elevated significantly following exertional stress at 14 degrees C. Exercise at 29 degrees C produced severe stress and marked physiological changes: heart rate, rectal and skin temperatures and cortisol levels increased significantly in both susceptible and resistant swine. At 29 degrees C, susceptible pigs also had higher levels of serum cortisol, total creatine kinase and MM isoenzyme (P less than 0.05) compared to resistant pigs. The results indicate that, following exertional or thermal stress, susceptible pigs undergo more extensive physiological changes than do resistant pigs. Similar levels of stress prior to slaughter may trigger physiological changes which in the susceptible pigs would likely result in pale, soft exudative myopathy.

Animals↗
PubMed1981

[Cerebrospinal fluid composition in newborn piglets].

Cerebrospinal fluid composition has been studied in low and normal birthweight piglets. Values for urea, Ca, K, Cl and P did not differ between the two groups. However, glucose concentration was lower in low birthweight subjects and Mg and Na values were higher. Total leukocytes were also higher in low birthweight piglets. These differences may suggest that blood-brain-barrier is not at the same stage of maturation in low birthweight as in normal birthweight subjects.

Animals↗
PubMed1980

Acute systemic anaphylaxis in adult domestic fowl: evidence for the protective role of H2-histaminergic and beta 2-adrenergic receptors.

Pentobarbital-anesthetized and spontaneously breathing, bovine albumin (BA)-sensitized adult domestic fowl showed acute systemic anaphylaxis to IV injection of antigen (BA), which was characterized by arterial hypotension, central venous hypertension, and bradycardia. Large doses of pyrilamine maleate (/1-receptor antagonist) partially inhibited acute systemic anaphylaxis. On the other hand, metiamide (a specific H2-antagonist) and propranolol (beta-adrenergic antagonist) markedly enhanced the anaphylactic response. Terbutaline (beta 2-agonist), dimaprit (a highly selective H2-agonist), and compound FPL 55712 (a slow-reacting substance of anaphylaxis receptor antagonist) either significantly inhibited or reversed the anaphylactic response. Cimetidine (a newer H2-antagonist) enhanced only central venous pressor response to BA. This investigation appears to suggest a minor role of histamine and a major role of slow-reacting substance of anaphylaxis as chemical mediatiors of anaphylaxis. A protective role of beta 2-adrenergic and H2-histaminergic receptors seem to operate in immediate hypersensitivity reactions in adult domestic fowl.

Anaphylaxis↗
PubMed1980

In vitro peripheral airway constriction to honey bee venom in cat.

Isolated lung parenchymal strips (peripheral airways) of cats responded to histamine, carbachol, 5-HT, bradykinin and honey bee-venom with concentration-dependent contractions. Atropine, mepyramine and methysergide inhibited or reversed contractions to carbachol, histamine and 5-HT respectively. Atropine, methysergide and indomethacin did not influence contractions to honey bee venom. High doses of mepyramine (H1-antagonist) inhibited or reversed the bee venom-induced contractions. These observations suggest that honey bee venom may be constricting cat peripheral airways by releasing endogenous histamine from the lung mast cells. Aceylcholine, 5-HY and prostaglandins appear to play little or no important role in the peripheral airway constrictions to honey bee venom in cat.

Animals↗
PubMed1980

Cranial measurements in the Arctic fox (Alopex lagopus).

The skulls of 36 adult arctic foxes (Alopex lagopus) of known sexes were measured in two Canadian subspecies. Significant differences (P less than or equal to 0.05) were found within and between the sexes of the two subspecies of arctic foxes. The identification of sexes is easier in the subspecies innuitus than in the subspecies groenlandicus. When the sexes of both subspecies are considered, the distinction between innuitus and groenlandicus becomes much more difficult.

Animals↗
PubMed1980

Electrocardiographic parameters in the normal lactating Holstein cow.

Electrocardiographic parameters in the normal lactating Holstein cow have been measured, computed and analyzed. The study was conducted on 32 animals of a mean age of 4.7 years. The recordings of the 12 leads (I, II, III, aVR, aVL, aVF, CV(6)LU, CV(6)LL, CV(6)RL, CV(6)RU, V(10) and base-apex) were made with a three channel electrocardiograph calibrated at 20 mm/mV and 25 mm/s. Conduction parameters, waves, intervals and segments have been measured. The recordings were analyzed as to shape, polarity and amplitude of the P and T waves and the components of the QRS complex. The results are discussed in respect to the morphophysiological characterestics of the bovine heart.

Animals↗