Distribution of the blood flow supplied by the vertebral artery in rats: anatomical, functional and pharmacological aspects.

In rats, the vertebral artery make only a minor contribution to the blood perfusion of the ponto-medullary area. This was measured with radioactive microspheres and was confirmed by methylmetacrylate casts and local injection of a centrally acting hypotensive drug.     

Distribution of tunichrome and vanadium in sea squirt blood cells sorted by flow cytometry

Specialized blood cells of many tunicates accumulate high concentrations of vanadium and phenolic peptide pigments called tunichromes (TC). In order to determine whether V and TC reside in the same cells, Ascidia nigra and Ascidia ceratodes blood cell subpopulations were isolated by fluorescence-activated cell sorting (flow cytometry) and chemically analyzed. V was found in the spherical, green/grey signet ring cells, and to a lesser degree in the mulberry-shaped, yellow/green morula cells (MRs), whereas free TC was detected mainly in MRs.     

L-arginine and pancreatic islet blood flow in anesthetized rats

The aim of the present study was to see if L-arginine, which induces insulin release and is a precursor of the endothelial-derived relaxing factor nitric oxide, affects whole pancreatic and/or islet blood flow. For this purpose, anesthetized male Sprague-Dawley rats were injected intravenously with either saline or L-arginine (25, 100 or 250 mg/kg body weight). All doses of arginine caused a slight increase in blood glucose concentration, while the highest dose (250 mg/kg body weight) also increased insulin concentration. However, no changes in either mean arterial blood pressure, whole pancreatic or islet blood flow could be discerned with any of the doses of arginine used. It is concluded that insulin release is not necessarily associated with an increased islet blood perfusion.     

Influence of diazoxide on regional blood flow in rats

Zusammenfassung Der Einfluss von Diazoxid auf die Organdurchblutung der Ratten wurde mittels⁸⁶Rb untersucht. Eine signifikante Durchblutungssteigerung des Herzens (128% der Kontrollwerte) und der Schilddrüse (139%) konnte bis 150 sec nach i.v. Injektion von 5 mg Diazoxid nachgewiesen werden. Die Durchblutung der Milz hingegen sank rasch auf 45% der Kontrollwerte, wobei nach 150 sec Normalisierung eintrat.     

Sexual maturation in female rats: Hereditary,developmental and environmental aspects

Two physiological components of sexual maturation, vaginal opening and first estrus, apparently evolve similarly in Wistar and Sprague-Dawley rats. However, a bimodal distribution in the frequency of the days of vaginal opening is observed within a given strain, which is less related to heredity than to the timing and type of experiment. In addition, when the modulators of sexual maturation are reviewed, it can be observed that sensitivity to external stimuli can vary even within a strain. For a defined set of breeding conditions, one group of rats can be more susceptible to changes in the lighting regimen and not be affected by controlled stressors, while another group responds more to stress and less to light. The reason for susceptibility to one rather than another environmental factor under similar breeding conditions is not understood. In that context, it is difficult to evaluate the role of heredity when we cannot understand the full impact of the environment, not to mention maternal influence in fetal and early life. Using two lines of psychogenetically selected rats, it was possible to show that they had differences in sexual maturation, which strongly suggested a genetic predisposition. Nevertheless, the question arises as to whether the genetic locus directly affects organs implicated in sexual maturation or whether it acts on some unknown factor which only secondarily modifies sexual maturation. In summary, there is more need to understand the role of the environment, including that of the mother early in fetal and neonatal life. It is suggested that the mechanisms underlying organ growth are set for a given species, while developmental and environmental factors fix the timing of vaginal opening and first ovulation. In the rat, there appear to be two times which are preferred for vaginal opening, given the laboratory conditions that have been used in the last 20 or so years: an early period, at 31–35 days, and a late period, at 36–40 days. An explanation for this dichotomy would be that a combination of parameters (not necessarily always the same) is needed for vaginal opening. These parameters oscillate during sexual maturation with different frequencies, which can achieve resonance to lead to vaginal opening and ovulation only during given periods.     

Sexual maturation in female rats: hereditary, developmental and environmental aspects

Two physiological components of sexual maturation, vaginal opening and first estrus, apparently evolve similarly in Wistar and Sprague-Dawley rats. However, a bimodal distribution in the frequency of the days of vaginal opening is observed within a given strain, which is less related to heredity than to the timing and type of experiment. In addition, when the modulators of sexual maturation are reviewed, it can be observed that sensitivity to external stimuli can vary even within a strain. For a defined set of breeding conditions, one group of rats can be more susceptible to changes in the lighting regimen and not be affected by controlled stressors, while another group responds more to stress and less to light. The reason for susceptibility to one rather than another environmental factor under similar breeding conditions is not understood. In that context, it is difficult to evaluate the role of heredity when we cannot understand the full impact of the environment, not to mention maternal influence in fetal and early life. Using two lines of psychogenetically selected rats, it was possible to show that they had differences in sexual maturation, which strongly suggested a genetic predisposition. Nevertheless, the question arises as to whether the genetic locus directly affects organs implicated in sexual maturation or whether it acts on some unknown factor which only secondarily modifies sexual maturation. In summary, there is more need to understand the role of the environment, including that of the mother early in fetal and neonatal life. It is suggested that the mechanisms underlying organ growth are set for a given species, while developmental and environmental factors fix the timing of vaginal opening and first ovulation. In the rat, there appear to be two times which are preferred for vaginal opening, given the laboratory conditions that have been used in the last 20 or so years: an early period, at 31-35 days, and a late period, at 36-40 days. An explanation for this dichotomy would be that a combination of parameters (not necessarily always the same) is needed for vaginal opening. These parameters oscillate during sexual maturation with different frequencies, which can achieve resonance to lead to vaginal opening and ovulation only during given periods.     

Effect of diabetes on the vertebral column of rats and its modification by estradiol

Summary In vertebrae of genetically selected sucrose-fed diabetic rats a statistically significant bone deficit was found after diabetes had been present for about 8 months. No osteopenia was observed in diabetic rats following treatment with estrogenic hormone for 5–7 months. The development of osseous centers in the end plates of the vertebrae was retarded in diabetic rats, but was about normal in diabetic rats given estrogen.—No differences were noted in the growth zones or in the tendency to develop articular lesions in rats of the various groups. Possible differences in the amount of GAG in intervertebral discs of diabetic and non-diabetic rats respectively await further confirmation.These investigations were aided by grant No. 2 RO1 EYO 1837-03, of the Institute of Arthritis and Metabolic Disease, National Institutes of Health, Bethesda, Maryland, USA.We are indebted to Professor Dr J. Rüttner, Institute of Pathology, University of Zürich, for his permission to use the calculator.     

Glomerular filtration rate and kidney blood flow in alloxan and streptozotocin diabetic rats

Summary Glomerular filtration rate (GFR), cardiac output, regional blood flow and kidney weight were measured in alloxan and streptozotocin diabetic rats at different times after the administration of diabetogen. A high GFR was found together with increased kidney weight and reduced blood flow.     

Capillary blood flow in sheep ovaries,measured by iodoantipyrine and microsphere techniques

Résumé La circulation capillaire du sang dans les ovaires des moutons a été mesurée en se servant des techniques d'iodoantipyrine radioactive et de microsphère (15±5 m diamètre). Pour les tissus non-lutéine, les estimations de circulation capillaire du sang obtenues par les deux méthodes furent similaires; pour les corpora lutea, les estimations obtenues avec les microsphères étaient, en moyenne, 7 fois plus grande que celles obtenues avec I'iodoantipyrine comme indicateur.     

The effect of guanethidine treatment of testicular blood flow and testosterone production in rats

Testicular blood flow was measured by means of Xenon-133 clearance in control rats and rats treated with guanethidine for 3 weeks. Plasma and testis testosterone concentrations were also measured, and the effect of hCG-treatment was examined. No difference in testicular blood flow between the control group and the guanethidine-treated group was found. However, in guanethidine-treated rats, plasma and testis testosterone concentrations after hCG-treatment were significantly decreased. The results may indicate that adrenergic nerves are involved in the regulation of Leydig cell function.     

The effect of guanethidine treatment of testicular blood flow and testosterone production in rats

Summary Testicular blood flow was measured bymeans of Xenon-133 clearance in control rats and rats treated with guanethidine for 3 weeks. Plasma and testis testosterone concentrations were also measured, and the effect of hCG-treatment was examined. No difference in testicular blood flow between the control group and the guanethidinetreated group was found. However, in guanethidine-treated rats, plasma and testis testosterone concentrations after hCG-treatment were significantly decreased. The results may indicate that adrenergic nerves are involved in the regulation of Leydig cell function.     

Hemodynamic and pharmacological aspects of the biphasic pressor response to acetylcholine in atropinized dogs

Zusammenfassung Es wird der Blutdruckanstieg nach Acetylcholin bei Atropin- und Physostigmin-vorbehandelten Hunden untersucht und unter Benützung von -Blockern analysiert. Es ergibt sich ein komplexe Bild, an dem offenbar mehrere Faktoren beteiligt sind.     

Glomerular filtration rate and kidney blood flow in alloxan and streptozotocin diabetic rats.

Glomerular filtration rate (GFR), cardiac output, regional blood flow and kidney weight were measured in alloxan and streptozotocin diabetic rats at different times after the administration of diabetogen. A high GFR was found together with increased kidney weight and reduced blood flow.     

The effect of dehydration on the neurohypophyseal blood flow in rats with hereditary diabetes insipidus

Summary Neurohypophyseal blood flow increases in water-deprived rats. This increase is independent of vasopressin release, since it occurs even in rats with hereditary defect of hypothalamic vasopressin synthesis.Acknowledgment. The technical assistance of D. Vilimovská is acknowledged.     

The effect of dehydration on the neurohypophyseal blood flow in rats with hereditary diabetes insipidus

Neurohypophyseal blood flow increases in water-deprived rats. This increase is independent of vasopressin release, since it occurs even in rats with hereditary defect of hypothalamic vasopressin synthesis.     

Intrarenal redistribution of the organ blood flow,induced by bleeding or hemorrhagic shock

Zusammenfassung Es wird eine durch Blutung und hämorrhagischen Schock hervorgerufene intrarenale Neuverteilung der Durchblutung beschrieben. Der wesentliche Effekt ist eine verminderte Blutversorgung der äussern Markzone.