Progesterone regulation of vascular thromboxane A(2) receptors in rhesus monkeys

We hypothesized that progesterone regulates thromboxane A(2) receptor (TxA(2)R) density in primate vascular muscle and that TxA(2)R density correlates with coronary reactivity in vivo and in vitro. Reactivity to serotonin + U-46619 was determined by angiography in surgically postmenopausal [ovariectomized (Ovx)] rhesus monkeys without progesterone replacement and after 2-wk progesterone treatment (1-2 ng/ml). In untreated Ovx animals, 100 micromol/l serotonin + 1 micromol/l U-46619 (syringe concentrations) provoked vasospasm-like constrictions in six of six monkeys; zero of six progesterone-treated monkeys developed vasospasms. Sustained Ca(2+) responses in vascular muscle cells isolated from Ovx coronaries (208 +/- 63% of basal 20 min after stimulation) treated with serotonin + U-46619 contrasted with transient Ca(2+) responses (143 +/- 18% of basal and decreasing 5 min after stimulation) in progesterone-treated monkeys. The maximum density of [1S-(1I,2J(5Z),3I(1E,3R*),4I)]-7-[3-(3-hydroxy-4-(4'-[(125)I]iodophenoxy)- 1-butenyl)-7-oxabicyclo[2.2.1]heptan-2-yl]-5-heptenoic acid ([(125)I]-BOP) binding was greater (P < 0.01) in carotid arteries and aortic membranes from Ovx (109 +/- 11 fmol/mg) compared with progesterone-treated (43 +/- 15 fmol/mg) monkeys. TxA(2)R immunolabeling revealed greater coronary TxA(2)R labeling in Ovx compared with progesterone-treated monkeys. The results suggest that progesterone can decrease arterial TxA(2)R in Ovx monkeys.     

The role of endogenous gonadotropin-releasing hormone in the control of luteinizing hormone and testosterone secretion in the juvenile male monkey, Macaca fascicularis

To determine what changes occur in the activity of gonadotropin-releasing hormone (GnRH) neurons during pubertal development in primate species we tested the hypotheses that there are morphologic differences between GnRH-containing neurons in juvenile versus adult monkeys, and the low activity of the reproductive axis is governed by hypothalamic GnRH release in monkeys prior to puberty. We removed the brains from 5 juvenile and 5 adult male monkeys (Macaca fascicularis) and blocked, sectioned, and prepared each hypothalamus for light microscopic immunocytochemistry for GnRH-containing cells. The distribution and number of GnRH-containing neurons were similar in adult and juvenile brains; however, GnRH-containing perikarya in adult brains were significantly larger in total cross-sectional area (200 +/- 12 vs. 169 +/- 8 micron 2, P less than 0.05) and in cross-sectional area of the cytoplasm (139 +/- 2 vs. 88 +/- 6 micron 2, P less than 0.05) than in juvenile brains. In another group of 10 juvenile male macaques, we administered an antiserum to GnRH (Fraser #94; 2 ml/kg, i.v.) and monitored the effects on plasma luteinizing hormone (LH) and testosterone concentrations. The percentage of plasma samples with detectable LH levels decreased significantly (from 26.67 +/- 8.3% to 5.3 +/- 3.4%, P less than 0.05) after GnRH antiserum administration; however, plasma testosterone concentrations (0.08 +/- 0.02 ng/ml) remained unchanged. We conclude that during pubertal maturation in primate species there is increased synthesis and release of GnRH from a population of GnRH neurons that are active prior to puberty.     

Growth curves of body weight and their relationship to sexual maturity in laboratory-bred male African green monkeys (Cercopithecus aethiops)

Nonlinear growth models having a three- or four-parameter family were applied to individual body weight data of 5 male African green monkeys for estimating their growth patterns. Body weight was measured from birth to six years of age and 58 to 114 data items per monkey were collected. The average body weight at birth was 360g with the standard deviation of +/- 25g, 4.54 +/- 0.29 kg at five years of age, and 4.50 +/- 0.12 kg at six years of age at which point body weight was judged to have reached a plateau. Five growth models (Gompertz, Logistic, Richards, Bertalanffy and Brody) were applied to the growth data in this study. As a result, two (Gompertz and Logistic) of the five models were found applicable to all data from the five monkeys. However, the coefficient of determination (R2) obtained by application of the two models were not so large (0.919 +/- 0.05 in Gompertz, 0.889 +/- 0.01 in Logistic). Therefore the data were divided into two groups according to monkey age: the first group being from monkeys between birth and 2 years 10 months of age and the second group was from monkeys older than 2 years 10 months of age. The Gompertz model fitted best the data of the first group in four of the five animals (R2 = 0.982 +/- 0.011). The age at the inflexion point in the Gompertz model nearly corresponded to the age of weaning. The Logistic model was most suitable for the date of the second group in all five animals (R2 = 0.955 +/- 0.038).(ABSTRACT TRUNCATED AT 250 WORDS)     

Interneurons of the motor region of the neocortex]

Interneurons of motor area in the brain cortex have been studied in cats and monkeys. The greatest attention has been paid to pyramidal interneurons, among which six cell types have been described according to their axonal composition. Unlike stellate interneurons, all types of pyramidal interneurons possess less developed axonal collaterals. Interneuronal contacts are situated on dendrites or cell bodies of middle and large long-axonal pyramids. Functional role of cortical interneurons seems to be different. Some of them are of inhibitory nature (basket cells and, perhaps, other types of long-axonal stellate neurons), others are exciting elements. The latter include short-axonal stellate neurons and, perhaps, pyramidal interneurons. While comparing the cortex in cats and monkeys, it is evident that the neocortex in monkeys, especially its lower layers, is rich in pyramidal interneurons.     

Body condition of feral cats and the effect of neutering

Considerable debate exists regarding the most appropriate methods for controlling feral cat populations, both from humane and logistical points of view. The physical condition of feral cats has not been reported, and it is not known if these cats benefit from neutering. This study investigates the body condition of feral cats by measuring body weight (BW), body condition score (BCS; Burkholder, 2000; Laflamme, Kealy, & Schmidt, 1994), and falciform fat pad. The study includes lateral abdominal radiographs taken at the time of neutering of 105 adult feral cats for measurement of falciform fat pad depth and area. At that time we also assessed BW and BCS. One year later we assessed the effects of neutering on body condition by evaluating a subsample of 14 cats. At the time of surgery, the cats were lean but not emaciated (BW 3.1 +/- 0.9 kg; BCS 4 +/- 1; based on a 1 to 9 scale ranging from 1 [emaciated] to 9 [grossly obese]). Falciform fat pad depth and area averaged 7.1 mm and 197.4 mm2, respectively, indicating a small amount of fat. Fourteen cats, reevaluated 1 year after neutering, increased 260% + 90% in falciform fat pad depth, 420% +/- 390% in fat pad area, 40% +/- 4% in BW, and 1 level in BCS ranking (1 to 9 scale; all differences p <.001). Similar to confined socialized cats, feral cats gained significant weight and body fat after neutering.     

Body surface areas and K values in strain 13 guinea pigs with different body weights and ages

Body surface areas (BSA) were determined for strain 13 guinea pigs with body weights ranging from 191 to 1011 g. For this determination, the entire skin of each animal was removed immediately after death and flattened on a wax film with a homogeneous paper. The skin outlines on the paper were cut and weighed for determining BSA. The K value was calculated for each guinea pig as the ratio of BSA (cm2)/body weight (g)2/3. Significantly different K values of 11.31 +/- 0.11, 9.66 +/- 0.09, 9.22 +/- 0.05, and 9.17 +/- 0.05 were determined for average body weights of 218 +/- 24, 527 +/- 33, 706 +/- 60, and 943 +/- 30 g, respectively. By plotting these K values on semilog paper and determining the best fit curve of the slope, it was possible to extrapolate exponentially the K values for different body weights. The relationship between age and body weight was also established for guinea pigs, and a series of K values were determined from birth to 35 weeks of life. We conclude that a different K value should be used for calculating BSA for various ages and body weights of strain 13 guinea pigs.     

Development of gastric acid secretion in pigs from birth to thirty six days of age: the response to pentagastrin

The development of the gastric acid secretory response to pentagastrin was studied using 56 Large White x Landrace pigs, 0-36 days of age, 1.1-13.3 kg body-weight, obtained from 12 litters. Gastric acid secretory capacity was measured using a gastric perfusion technique and intravenous infusion of pentagastrin at dose rates of 2, 4 and 8 micrograms/h per kg. Significant positive linear correlations were found between stomach weight and age, and between stomach weight and body-weight during the 36 day period. The stomach weight to body-weight ratio increased for the first 3 days of age and then decreased during the following 33 days. Basal acid secretion was detected in all unsuckled pigs (n = 9), 2- to 8-h old. Maximal acid outputs in response to pentagastrin in these pigs were 0.16 +/- 0.02 mmol/kg body-weight and 0.034 +/- 0.001 mmol/g stomach weight. For the 56 pigs, significant linear correlations were found between maximal acid output and age, maximal acid output and body-weight, and maximal acid output and stomach weight. There was a significant linear increase in maximal acid output per unit stomach weight during the first 7 days of age, but during the subsequent 29 days the pattern of increase in gastric secretory capacity was slower and curvilinear. In the oldest nine pigs, 24-36 days of age, maximal acid outputs were 0.974 +/- 0.058 mmol/kg body-weight and 0.234 +/- 0.016 mmol/g stomach weight which represents a six to seven-fold increase compared with those determined in pigs at birth. Comparison of gastric acid secretory capacity determined under anaesthesia with that in conscious pigs showed that anaesthesia appeared to suppress basal output but had no effect on pentagastrin stimulated output. Comparison of response to histalog (betazole HCl) and pentagastrin indicated that newborn pigs were more sensitive to histalog but in pigs 9-38 days of age, there were no significant differences in responsiveness to the two secretagogues. These results show that gastric sensitivity to pentagastrin increases rapidly in the first week of life, that the stomach of the newborn pig is more sensitive to histalog than pentagastrin and that studies of the effect of pentagastrin on acid secretion, done under anaesthesia, are comparable to those in the conscious pig.     

Comparative immunological and electrophoretic analysis of Gc protein in sera from various animals

1. On immunodiffusion, using an anti-human Gc antibody, serum Gc in all mammals tested revealed a partial identity with human Gc. 2. The relative cross-reactivities of serum Gc in monkeys, dogs, cats and rats with human Gc antiserum were found to be more than 70% while the serum Gc in other mammals (pigs, cattle, goats and a guinea pig) was less than 50%. 3. Testing, using the isoelectrofocusing method, showed specific patterns of Gc in the mammals. In the sera of cats and cattle, Gc polymorphisms were detected. 4. Neuraminidase treatment affected the isoelectrofocusing Gc patterns of pigs, goats and cattle, whereas those in other mammals remained unchanged.     

Biphasic effect of a prostacyclin methyl ester analog on uterine contractility in the chronically catheterized pregnant rhesus monkey in late gestation

We determined the in vivo effects of a prostacyclin methyl ester analog (PGI2) administration on myometrial activity in twelve chronically- catheterized pregnant rhesus monkeys during the last third of pregnancy under three different states of myometrial contractility: postsurgical contractions, spontaneous contractures and oxytocin induced contractions. Prostacyclin (200 micrograms) was administered to four monkeys 2-3 h after surgery, to eight monkeys having only contractures, and to four monkeys having oxytocin induced contractions. Vehicle administration was performed in six animals having contractures and to four having oxytocin induced contractions. In all three experimental paradigms PGI2 administration elicited a biphasic response in uterine contractility. An initial increase in the 5 min average intrauterine pressure (IUP) value from 2.3 +/- 1.29 to 5.8 +/- 2.29; 3.6 +/- 2.38 to 7.6 +/- 3.59; and 2.3 +/- 0.65 to 8.6 +/- 0.72 (SD); was observed in the post-surgical, spontaneous contracture and oxytocin induced contraction groups respectively (mmHg, P less than 0.05). This increase was followed by a fall in the 5 min average IUP from 2.3 +/- 1.29 to 0.6 +/- 0.49; 3.6 +/- 2.38 to 1.3 +/- 0.86; and 2.3 +/- 0.65 to 0.1 +/- 0.11 in the post-surgical, spontaneous contracture and oxytocin induced contraction groups respectively (mmHg, P less than 0.05). A fall in mean arterial blood pressure from 89 +/- 9.0 to 55 +/- 10.9 (mmHg, P less than 0.05) and a compensatory tachycardia from 108 +/- 18.2 to 164 +/- 56.2 (beats.min-1, P less than 0.05) was observed by 10 min after PGI2 administration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Genetic limitations of erythrocyte lysis by bacteria of the genus Salmonella]

Lytic effect of Salmonella bacteria on the erythrocates of 1301 humans (including 150 twins), 1059 hens, 600 mice, 33 guinea pigs, 47 rabbits, 22 horses, 16 sheeps, 7 dogs, 2 cats and 2 monkeys was investigated. Erythrocytes of all horses, guinea pigs and rabbits tested appeared to be sensible. The same cells of humans, sheeps, hens, dogs, monkeys and cats turned to be either sensible, or stable. Human erythrocytes were the most stable. Erythrocytes of humans having had typhus or other Salmonella infections appeared to be more sensible. Homozygous twins developed complete two by two concordance of the sign of sensibility in all details investigated. Relation of erythrocytes to Salmonella hemolysins was not influences with time and specific immunization, did not correlate with blood groups and factors ABO, MN, P and rhesis systems, with age, sex and nationality of people tested. It also did not correlate with the presence of anti-salmonella agglutinins, with different osmotic and acid stability of erythrocytes. The display of hemolytic activity of Salmonella is limited by genetically predestinated species and individual properties of erythrocytes.     

Conditioned taste aversion and motion sickness in cats and squirrel monkeys

The relationship between vomiting and conditioned taste aversion was studied in intact cats and squirrel monkeys and in cats and squirrel monkeys in which the area postrema was ablated by thermal cautery. In cats conditioned 7-12 months after ablation of the area postrema, three successive treatments with xylazine failed to produce either vomiting or conditioned taste aversion to a novel fluid. Intact cats, however, vomited and formed a conditioned aversion. In squirrel monkeys conditioned 6 months after ablation of the area postrema, three treatments with lithium chloride failed to produce conditioned taste aversion. Intact monkeys did condition with these treatments. Neither intact nor ablated monkeys vomited or evidenced other signs of illness when injected with lithium chloride. When the same ablated cats and monkeys were exposed to a form of motion that produced vomiting prior to surgery, conditioned taste aversion was produced and some animals vomited. These findings confirm other studies indicating motion can produce vomiting in animals with the area postrema destroyed and demonstrate that motion-induced conditioned taste aversion can be produced after ablation of the area postrema. The utility of conditioned taste aversion as a measure of subemetic motion sickness is discussed by examining agreement and disagreement between identifications of motion sickness by conditioned taste aversion and vomiting. It is suggested that a convincing demonstration of the utility of conditioned taste aversion as a measure of nausea requires the identification of physiological correlates of nausea, and caution should be exercised when attempting to interpret conditioned taste aversion as a measure of nausea.     

Naloxone reduces ventilatory depression of brain hypoxia

To assess whether endogenous opioids participate in respiratory depression due to brain hypoxia, we determined the ventilatory response to progressive carboxyhemoglobinemia (1% CO, 40% O2) before and after administration of naloxone (NLX, 0.1 mg/kg iv). Minute ventilation (VI) and ventral medullary surface pH (Vm pH) were measured in six anesthetized, peripherally chemodenervated cats. NLX consistently increased base-line hyperoxic VI from 618 +/- 99 to 729 +/- 126 ml/min (P less than 0.05). Although NLX did not alter the Vm pH response to CO [initial alkalosis, Vm pH +0.011 +/- 0.003 pH units, followed by acidosis, Vm pH -0.082 +/- 0.036 at carboxyhemoglobin (HbCO) 55%], NLX attenuated the amount of ventilatory depression; increasing HbCO to 55% decreased VI to 66 +/- 6% of base line before NLX and to 81 +/- 9% of base line after NLX (P less than 0.05). The difference in response after NLX was primarily the result of a linear increase in tidal volume (VT) with decreasing Vm pH (delta VT = 60.3 ml/-pH unit) which was absent before NLX. To assess whether the site of action of the endogenous opioid effect was the central chemosensors, the ventilatory and Vm pH response to progressive HbCO was determined in three additional cats before and after topical application of NLX (3 X 10(-4) M) to the ventral medullary surface. The effect of topical NLX was similar to systemic NLX; significant attenuation of the reduction in VI with increasing HbCO. We conclude that 1) endogenous opioids mediate a portion of the depression of ventilation due to acute brain hypoxia, and 2) this effect is probably at the central chemosensitive regions.     

Effects of keratinase supplementation of corn-soybean meal based diets on apparent ileal amino acid digestibility in growing pigs and serum amino acids, cytokines, immunoglobulin levels and loin muscle area in nursery pigs

Two experiments were conducted to evaluate effects of keratinase for growing and nursery pigs. In Exp. 1, six pigs (32.3 +/- 2.8 kg body weight), fitted with a simple T-cannula at the distal ileum, were assigned to one of two 3 x 3 Latin squares involving three periods and three diets including a basal diet and the same diets supplemented with 0, 0.05 or 0.1% keratinase. Dietary keratinase supplementation increased the apparent ileal digestibility of crude protein (CP), arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, alanine, glutamic acid and proline (p < 0.05). Digestibility coefficients did not differ between pigs fed 0.05 and 0.1% keratinase. In Exp. 2, 24 piglets weaned at 30 +/- 2 d of age were used in a 2 x 2 factorial design experiment with two CP concentrations (19 vs. 22%) and two levels of keratinase supplementation (0 vs. 0.05%). Keratinase supplementation increased (p < 0.05) average daily gain, serum arginine concentration and loin muscle area but decreased (p < 0.05) serum interleukin-10 concentrations. The reduction in dietary CP level decreased (p < 0.05) serum urea nitrogen concentrations, isoleucine, serine and proline concentrations, but increased serum arginine concentrations. Few interactions between keratinase supplementation and dietary CP concentration were observed. This study indicated that dietary keratinase supplementation improved apparent ileal amino acid digestibility for growing pigs and had a positive effect on weight gain, immune response and loin muscle area for nursery pigs.     

The effect of unilateral ureteral obstruction on renal function in pigs measured by diffusion-weighted MRI

The objective of this study was to examine the effect of unilateral ureteral obstruction on the apparent diffusion coefficient (ADC) in pig kidney. Changes in ADC is suggested to reflect changes in the ratio of extracellular to intracellular volume. Thirteen pigs were allocated into three groups: 1) pigs subjected to acute unilateral ureteral obstruction (AUO) (n = 3), 2) pigs subjected to chronic partial unilateral obstruction (CPUO) (n = 3), and 3) control pigs (n = 7). The extra- to intracellular volume ratio was indirectly measured in both the ipsilateral obstructed kidney and contralateral non-obstructed kidney by the ADC of the renal tissue using diffusion-weighted echo-planar magnetic resonance imaging. ADC was 2.07 +/- 0.27 x 10(-3) mm2/s in the cortex and 2.10 +/- 0.24 x 10(-3) mm2/s in the medulla of normal control kidneys. In the obstructed kidney from the AUO group the ADC of the medulla was significantly reduced 24 hours after occlusion of the ureter (1.65 +/- 0.05 x 10(-3) mm2/s vs 2.10 +/- 0.24 x 10(-3) mm2/s; p < 0.05). Similarly ADC decreased slightly in the cortex of the ipsilateral kidney. In contrast, ADC of the ipsilateral kidney of CPUO pigs was increased both in the renal medulla (3.13 +/- 0.21 x 10(-3) mm2/s vs. 2.10 +/- 0.24 x 10(-3) mm2/s; p < 0.05) and cortex (3.09 +/- 0.14 x 10(-3) mm2/s vs. 2.07 x 10(-3) mm2/s, p < 0.05). In conclusion, the results of the present study suggest that diffusion weighted imaging (ADC) may be a useful parameter to incorporate when identifying whether a ureteric obstruction is acute or chronic.     

Medullary lateral tegmental field mediates the cardiovascular but not respiratory component of the Bezold-Jarisch reflex in the cat

We determined the effects of bilateral microinjection of muscimol and excitatory amino acid receptor antagonists into the medullary lateral tegmental field (LTF) on changes in sympathetic nerve discharge (SND), mean arterial pressure (MAP), and phrenic nerve activity (PNA; artificially ventilated cats) or intratracheal pressure (spontaneously breathing cats) elicited by right atrial administration of phenylbiguanide (PBG; i.e., the Bezold-Jarisch reflex) in dial-urethane anesthetized cats. The PBG-induced depressor response (-66 +/- 8 mmHg; mean +/- SE) was converted to a pressor response after muscimol microinjection in two of three spontaneously breathing cats and was markedly reduced in the other cat; however, the duration of apnea (20 +/- 3 vs. 17 +/- 7 s) was essentially unchanged. In seven paralyzed, artificially ventilated cats, muscimol microinjection significantly (P < 0.05) attenuated the PBG-induced fall in MAP (-39 +/- 7 vs. -4 +/- 4 mmHg) and the magnitude (-98 +/- 1 vs. -35 +/- 13%) and duration (15 +/- 2 vs. 3 +/- 2 s) of the sympathoinhibitory response. In contrast, the PBG-induced inhibition of PNA was unaffected (3 cats). Similar results were obtained by microinjection of an N-methyl-D-aspartate (NMDA) receptor antagonist, D(-)-2-amino-5-phosphonopentanoic acid, into the LTF. In contrast, neither the cardiovascular nor respiratory responses to PBG were altered by blockade of non-NMDA receptors with 1,2,3,4-tetrahydro-6-nitro-2,3-dioxobenzo[f]quinoxaline-7-sulfonamide. We conclude that the LTF subserves a critical role in mediating the sympathetic and cardiovascular components of the Bezold-Jarisch reflex. Moreover, these data show separation of the pathways mediating the respiratory and cardiovascular responses of this reflex at a level central to bulbospinal outflows to phrenic motoneurons and preganglionic sympathetic neurons.     

GnRH immunocontraception of male cats

The development of nonsurgical contraceptives for cats may facilitate population control of the species. The purpose of this study was to investigate the utility of GnRH for immunocontraception of male cats. Male cats (n=12) were divided into groups of three and were immunized once with 0 (sham), 50, 200, or 400 microg synthetic GnRH coupled to keyhole limpet hemocyanin and combined with a mycobacterial adjuvant to enhance immunogenicity. GnRH antibody titer, serum testosterone concentration, and scrotal size were determined monthly. At 6 months, semen was collected by electroejaculation and testes were examined histologically. GnRH antibodies were detected in all cats receiving GnRH vaccine by 1 month post-treatment and persisted throughout the study. No dose effect of GnRH was observed; titers were not different among cats treated with 50, 200, or 400 microg GnRH (P=0.5). Six of nine treated cats were classified as responders based on high GnRH antibody titers (>32,000). By 3 months post-treatment, responder cats had undetectable testosterone concentrations and testicular atrophy. Nonresponder cats had GnRH titers of 4000-32,000 and testosterone concentrations intermediate between responder and sham-treated cats. At 6 months, total sperm counts were similar for sham-treated cats (3.1+/-1.8 x 10(6) sperm) and nonresponder cats (3.4+/-1.6 x 10(6) sperm; P=0.7). Only one of the six responder cats produced sperm, none of which were motile. Combined testicular weights of responder cats (1.3+/-0.1 g) were lower than sham-treated controls (5.3+/-1.3 g; P=0.02) and nonresponder cats (2.9+/-0.3 g; P=0.02). Histologic evaluation of the testes revealed that in responder cats, the interstitial cells that were present were pale and shrunken compared to the plump, polyhedral eosinophilic cells in sham-treated cats. GnRH responder cats had marked tubular atrophy with vacuolated Sertoli cells and a paucity of germ cells. Single-dose GnRH treatment resulted in testosterone concentrations and semen quality consistent with immunocastration in a majority of cats treated.     

Ah receptor in spleen of rodent and primate species: detection by binding of 2,3,7,8-tetrachlorodibenzo-p-dioxin

In many species systemic toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is manifested by a generalized wasting syndrome accompanied by a variety of specific organ changes including atrophy of the thymus and spleen. TCDD toxicity in most tissues is thought to be mediated by the Ah receptor. Although the spleen is a prime target for TCDD toxicity, the possible presence of Ah receptor in the spleen has not previously been investigated. Specific binding of [3H]TCDD to Ah receptor in spleen cytosols was assessed by velocity sedimentation on sucrose gradients. Ah receptor was detected in spleen cytosols from adult Rhesus monkeys (mean +/- SEM, 36 +/- 8 fmol/mg cytosol protein), fetal Rhesus monkeys (9 +/- 6), Sprague-Dawley rats (20 +/- 5), C57BL/6J mice (18 +/- 2), New Zealand white rabbits (19 +/- 2), and Hartley guinea pigs (15 +/- 2). Ah receptor was not detectable in spleen cytosol from genetically "nonresponsive" DBA/2J mice or from Golden Syrian hamsters, a species resistant to toxicity of TCDD. Molecular properties of Ah receptor from spleen were similar to those of the receptor from liver of the same species. The high Ah receptor content in spleen cytosols from those species that are most susceptible to TCDD toxicity is consistent with the view that the Ah receptor mediates TCDD toxicity in spleen as well as in other tissues.     

Exercise-induced cardiac hypertrophy: a correlation of blood flow and microvasculature

The effects of exercise conditioning on the myocardium were studied in seven instrumented pigs strenuously exercised for 12 wk by treadmill running. Data were compared with eight instrumented untrained pigs. O2 consumption measured during maximum exercise effort was significantly elevated in the trained pigs (71.7 +/- 4.0 vs. 56.3 +/- 3.0 ml X ml-1 X kg-1). Absolute right and left ventricular mass increased by 20 and 13%, respectively, in response to exercise. Myocyte cross-sectional area increased by 21% in the trained hearts compared with the untrained hearts. Transmural left ventricular myocardial blood flow (ml X min-1 X g-1) was not significantly different at rest, during maximum exercise, or during exercise with adenosine infusion. However, training caused an elevation of the regional epicardial blood flow noted during exercise and exercise with adenosine. In the trained pigs mean aortic pressure during maximum exercise with adenosine infusion was not significantly different compared with untrained pigs. Coronary resistance during exercise with adenosine infusion was the same in both animal groups. In the trained group capillary numerical (no./mm2) and length (mm/mm3) densities were reduced, whereas arteriolar numerical and length densities were significantly increased compared with the untrained group. Measurements of capillary luminal surface density (mm2/mm3) in the trained group were unchanged compared with the untrained group. These results suggest that strenuous exercise does not stimulate the production of new capillaries, but this is modified by the ability of existing capillaries to increase their luminal surface area to parallel increases in myocyte growth. The arteriolar data suggest that exercise promotes the formation of new arterioles.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of pregnancy on ventilatory and carotid body neural output responsiveness to hypoxia in cats

Pregnancy increases ventilation and ventilatory sensitivity to hypoxia and hypercapnia. To determine the role of the carotid body in the increased hypoxic ventilatory response, we measured ventilation and carotid body neural output (CBNO) during progressive isocapnic hypoxia in 15 anesthetized near-term pregnant cats and 15 nonpregnant females. The pregnant compared with nonpregnant cats had greater room-air ventilation [1.48 +/- 0.24 vs. 0.45 +/- 0.05 (SE) l/min BTPS, P less than 0.01], O2 consumption (29 +/- 2 vs. 19 +/- 1 ml/min STPD, P less than 0.01), and lower end-tidal PCO2 (30 +/- 1 vs. 35 +/- 1 Torr, P less than 0.01). Lower end-tidal CO2 tensions were also observed in seven awake pregnant compared with seven awake nonpregnant cats (28 +/- 1 vs. 31 +/- 1 Torr, P less than 0.05). The ventilatory response to hypoxia as measured by the shape of parameter A was twofold greater (38 +/- 5 vs. 17 +/- 3, P less than 0.01) in the anesthetized pregnant compared with nonpregnant cats, and the CBNO response to hypoxia was also increased twofold (58 +/- 11 vs. 29 +/- 5, P less than 0.05). The increased CBNO response to hypoxia in the pregnant compared with the nonpregnant cats persisted after cutting the carotid sinus nerve while recording from the distal end, indicating that the increased hypoxic sensitivity was not due to descending central neural influences. We concluded that greater carotid body sensitivity to hypoxia contributed to the increased hypoxic ventilatory responsiveness observed in pregnant cats.     

Karyotypes of Pneumocystis carinii derived from several mammals

Pneumocystis carinii is the most important opportunistic pathogen of humans in the world. Pneumocystis carinii is experimentally detected in the lungs of rats, mice, rabbits, and monkeys, however, the organisms from different mammals are identical in microscopic morphology. The present study tried to find out more mammalian hosts of P. carinii and also to differentiate the organisms from different mammals by karyotyping. Rats, mice, hamsters, rabbits, cats, and dogs were successfully infected by P. carinii, but guinea pigs and pigs were not. Karyotype of P. carinii from rabbits showed similar size range of chromosomes with that of the prototype, but in different pattern. The patterns from cats and dogs were also different from that of rats. The present study confirms that cats and dogs are infected by P. carinii and at least total three karyotype strains of P. carinii are proven in Korea.