ABSTRACT
Central command, which is a neural drive originating in the brain during exercise, regulates the sympathetic nervous system and evokes cardiovascular responses to exercise. To examine the role of the central command on sympathetic regulation of renal circulation, we compared responses in renal cortical blood flow and vascular conductance to electrical stimulation of mesencephalic locomotor region (MLR) for 30 s in decerebrate and paralyzed rats between renal nerves that were intact (n=8) and denervated (n=8). In rats with renal nerves intact, stimulation of the MLR at 40 microA current intensity significantly (p<0.05) decreased renal cortical blood flow (-17+/-5%, means+/-S.E.M.) and vascular conductance (-43+/-4%) and the decrease in renal vascular conductance was dependent on current intensity (between 20 and 60 microA). In renal denervated rats, in contrast, there were no significant changes in either renal cortical blood flow or vascular conductance during stimulation at all current intensities. In a subset of rats (n=8), the response in renal sympathetic nerve activity to 30 s stimulation of the MLR was investigated. Stimulation of the MLR significantly increased renal sympathetic nerve activity (+57+/-14% at 40 microA) and the response was dependent on current intensity (between 20 and 60 microA). These data provide evidence that central command induces renal vasoconstriction by increasing sympathetic activity, depending on central command intensity.
Subject(s)
Kidney/blood supply , Mesencephalon/physiology , Renal Circulation/physiology , Sympathectomy , Vasoconstriction/physiology , Adrenergic Fibers/physiology , Adrenergic Fibers/radiation effects , Animals , Blood Pressure/radiation effects , Decerebrate State/physiopathology , Dose-Response Relationship, Radiation , Electric Stimulation/methods , Heart Rate/radiation effects , Laser-Doppler Flowmetry/methods , Male , Mesencephalon/radiation effects , Rats , Rats, Sprague-Dawley , Vasoconstriction/drug effectsABSTRACT
Schwann cells, from a variety of sources, are known to possess P2Y purinergic metabotropic receptors. However, it is not known if Schwann cells associated with autonomic nerve terminals possess such receptors and if so whether these receptors are activated by the endogenous release of ATP from the nerve terminals. We show that such Schwann cells in the vas deferens give evoked calcium transients on nerve stimulation. These transients are mediated, at least in part, by the endogenous release of ATP, which acts on Schwann cell P2Y receptors to release calcium from within the cells. This work suggests the possibility that Schwann cells are active participants in the process of junctional transmission in the autonomic nervous system.
Subject(s)
Adenosine Triphosphate/pharmacology , Pyridoxal Phosphate/analogs & derivatives , Schwann Cells/drug effects , Vas Deferens/cytology , Adrenergic Fibers/radiation effects , Aniline Compounds , Animals , Caffeine/pharmacology , Calcium/metabolism , Calcium/pharmacology , Cell Count/methods , Drug Interactions , Electric Stimulation/methods , Estrenes/pharmacology , Evoked Potentials/drug effects , Fluorescent Dyes/metabolism , Immunohistochemistry/methods , In Vitro Techniques , Male , Mice , Mice, Inbred BALB C , Organic Chemicals , Phosphodiesterase Inhibitors/pharmacology , Platelet Aggregation Inhibitors/pharmacology , Pyridoxal Phosphate/pharmacology , Pyrrolidinones/pharmacology , Quinazolines/pharmacology , S100 Proteins/metabolism , Schwann Cells/physiology , Suramin/pharmacology , Time Factors , Triazoles/pharmacology , Uridine Triphosphate/pharmacology , Vas Deferens/drug effects , XanthenesABSTRACT
State and structural organization of the guinea pig thyroid gland were studied histochemically in distanced terms (6 months) after the single external x-ray radiation 12.9 C/kg in doze. with the following intraperitoneal introduction of 131 6.5 C/kg in doze. Atrophically changed zones of parenchyma were observed along with regions of extra- and intrafollicular hyperplasia with compensatory-adaptive manifestations aimed at hormonopoiesis increase. Growth of sympathetic innervation of the vessel walls and around the follicles were found in areas of high functional activity. Direct contact between adrenergic axons and thyrocytes was demonstrated by means of electron microscopy. In parenchyma areas with signs of atrophia, adrenergic nerve fibers and terminals are located only in vessels. Thus, connection between the state of the thyroid gland sympathetic innervation and structural organization of its parenchyma in distanced terms of radiational effects was followed up.
Subject(s)
Thyroid Gland/innervation , Thyroid Gland/radiation effects , Adrenergic Fibers/radiation effects , Adrenergic Fibers/ultrastructure , Animals , Female , Gamma Rays , Guinea Pigs , Iodine Radioisotopes , Microscopy, Electron , Sympathetic Nervous System/radiation effects , Sympathetic Nervous System/ultrastructure , Thyroid Gland/ultrastructure , Time FactorsABSTRACT
X-irradiation of the rat neonatal hippocampus produces severe alterations in the architectonic features of the mature hippocampus. The most prominent alterations is a marked depletion of the granule cells of the dentate gyrus, with a subsequent realignment of CA 4 cells. The present data also show that norepinephrine (NE), dopamine and histamine stimulation of adenylate cyclase activity is severely attenuated in the hippocampi of irradiated animals. This failure suggests that the NE fibers of irradiated subjects, although normal in content of NE, are not functional in some of their NE-effector actions.
Subject(s)
Adenylyl Cyclases/metabolism , Dopamine/pharmacology , Hippocampus/radiation effects , Histamine/pharmacology , Norepinephrine/radiation effects , Adrenergic Fibers/radiation effects , Animals , Cyclic AMP/metabolism , Dose-Response Relationship, Drug , Female , Hippocampus/enzymology , Male , Neurons/radiation effects , RatsABSTRACT
The influence of continuous light or darkness on the large granulated vesicles in sympathetic nerve fibers of the mouse pineal was investigated by means of quantitative electron microscopic techniques. Continuous illumination at about 20 lux caused the disappearance of the diurnal rhythm in the number of the large granulated vesicles, followed by an accumulation of these vesicles. The diurnal rhythm of the large granulated vesicles was abolished in mice kept in continuous darkness for 7 days. These results suggest that the diurnal variation of the large granulated vesicles may be controlled directly by environmental light. Based on these findings, the relationships between small and large granulated vesicles were discussed.
