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131.
Rats with selective brain dopamine-depleting lesions produced by 6-hydroxydopamine failed to increase their food intake after 2-deoxy-D-glucose administration. Their hyperglycemic response to 2DG was identical to that of intact controls. Neither group showed significant mobilization of free fatty acids or production of ketones. 相似文献
132.
Rats were permanently hypodipsic when offered a quinine adulterated fluid on a chronic basis. Plasma osmolarity and Na concentration were normal, but the quinine drinkers showed a slight hyperkalemia compared to water drinking controls. The quinine-drinking rats maintained hydromineral equilibrium through the excretion of a small amount of concentrated urine. The quinine intake was closely matched to need, and fell to near zero when food was removed or water was supplied intravenously. This harmony of intake and output was disrupted after acute hypertonic NaCl load: while the obligatory salt diuresis was no different between water and quinine drinkers, the latter did not drink (except at the lowest level of adulteration) within several hours. However, by 24 hr all had shown a delayed drinking response. This delay in drinking of quinine was also evident after non-painful intravenous NaCl infusions, but no drinking occurred after nephrectomy. Quinine drinkers were also unresponsive to isoproterenol and intracranial dipsogens. These data are discussed in terms of their implication for definitions of regulatory drinking behavior. 相似文献
133.
134.
Neil A. Castle 《Pflügers Archiv : European journal of physiology》1989,415(3):322-329
The effect of forskolin on voltage-activated Na+ and K+ currents in nodes of Ranvier from the toad, Bufo marinus, has been examined using the vaseline-gap voltageclamp technique. Peak Na+ currents (I
Na) were reduced by 35% and the rate of decline of Na+ current during continuous depolarization was accelerated following treatment with 450 M forskolin. However, the voltage-dependence of steady-state inactivation as well as the rate of recovery from fast inactivation remained unchanged. Upon repetitive depolarization at 1–10 Hz, a further inhibition of I
Na (60%) was observed. This use-dependent or phasic inhibition recovers slowly at -80 mV ( 13 s) and had a voltage-dependence like that of activation of the Na conductance. Near maximal steady-state phasic inhibition occurred with depolarizing pulse durations of only 4 ms, consistent with a direct involvement of the open Na+ channel in the blocking process. Inhibition of the delayed K+ current (I
K) was characterized by a concentration-dependent reduction in steady-state current amplitude (IC50 80 M) and a concentration-independent acceleration of current inactivation. A similar inhibition of I
K was obtained with 1,9-dideoxyforskolin, a homolog which does not activate adenylate cyclase (AC). The results suggest that the inhibition of I
K and perhaps I
Na follows directly from drug binding and is not a consequence of AC activation. 相似文献
135.
Tapan Kumar Bhattacharyya David Gordon Butler 《Anatomical record (Hoboken, N.J. : 2007)》1979,193(2):213-231
The ultrastructure of the adrenocortical homologue (AH) of the north American eel (Anguilla rostrata) was studied from freshwater and long-term (1.5 years) seawater (SW) adpated animals. The AH tissue situated in the wall of cardinal veins is surrounded by a thin layer of collagenous capsule; in the region away from the vein wall, parenchymal cells are separated by interstitial lacunae containing collagen bundles, capillaries, chromaffin cells and nerve fibers often applied closely to the surface of AH cells. The free surface of the cell near the vein wall, capillaries or interstitial space extends numerous slender microplicae. The cytoplasm is characterized by the presence of mitochondria with tubular cristae, a network of smooth endoplasmic reticulum, a few cisternae of rough surfaced endoplasmic reticulum, well developed Golgi apparatus, coated vesicles, centrioles, cilium, filaments, microtubules, dense bodies of variable nature and a scarcity of liposomes. The cell nuclei possess invaginated cytoplasmic pseudo-inclusions. Electron histochemical reaction for free cholesterol revealed the occurrence of needle-shaped crystals mainly associated with surface microplicae and smooth endoplasmic reticulum, which seems to be the major organelle for storage or synthesis of this steroid precursor. SW animals indicated ultrastructural signs of stimulated steroid synthesis and secretion, i.e., high degree of pseudo-follicle formation, increased electron density of mitochondria, greater abundance of lysosomal dense bodies, hyperactivity of Golgi apparatus and dilation of smooth endoplasmic reticulum tubules. Some SW fishes showed extensive deposition of osmiophilic inclusions in the mitochondria and stacks of elongated cup-shaped mitochondria. Chronic seawater acclimation enhances AH activity as judged by ultrastructural criteria with ultimate mitochondrial degeneration resulting possibly from prolonged cortisol hypersecretion; the latter may be linked with physiologic re-adjustment of ionic transfer mechanism in hyperosmotic medium. 相似文献
136.
137.
The ligand for the T cell antigen CD2 is CD48 in rodents, but CD58 in humans. The extracelluar parts of these three antigens are structurally related in that all contain two immunoglobulin superfamily (IgSF) domains. There have been reports of alternative ligands for CD2 in the human, but not so far in rodents. We describe the analysis of ligands for rat CD2 and CD48 using fluorescent beads capable of displaying a high ligand density and detecting low-affinity interactions like that of CD2 with CD48 (Kd = 60 ? 90 μM). Monovalent chimeric proteins containing the two IgSF domains of rat CD48 or CD2 and domains 3 and 4 of rat CD4 (CD4d3+4) were anchored to fluorescent covaspheresTM via a CD4 monoclonal antibody (mAb) with the CD48 or CD2 domains available for ligand binding. Multivalent CD48-CD4d3 + 4 covaspheresTM gave strong specific binding to rat CD2 expressed on the surface of transfected Jurkat cells. CD48-CD4d3+4 was compared with CD48-IgG and CD48-IgM as tools for detecting binding at the cell surface. Soluble divalent CD48-IgG and decavalent CD48-IgM bound to soluble CD2 with a Koff of around 10?3 s?1 as determined using a BIAcoreTM biosensor. However, binding to cells by CD48-IgG and CD48-IgM was only detectable when they were immobilized on covaspheresTM and represented no increase in sensitivity over CD48-CD4 covaspheresTM when tested for binding to cells expressing high and low levels of CD2. CD48-CD4d3 + 4 covaspheresTM only bound to rat cells expressing CD2. In the reverse orientation, binding of CD2-CD4d3 + 4 covaspheresTM was dependent on expression of CD48. Pre-incubation of cells with CD2 or CD48 mAb abolished all binding of CD48-CD4d3 + 4 or CD2-CD4d3 + 4, respectively. The data provide no evidence for an alternative ligand for rat CD2 or CD48. 相似文献
138.
139.
Jim R. Wilson Neil A. Duncan Wayne R. Giles Robert B. Clark 《The Journal of physiology》2004,557(1):93-104
The electrophysiological properties of acutely isolated canine articular chondrocytes have been characterized using patch-clamp methods. The 'steady-state' current–voltage relationship ( I–V ) of single chondrocytes over the range of potentials from −100 to +40 mV was highly non-linear, showing strong outward rectification positive to the zero-current potential. Currents activated at membrane potentials negative to −50 mV were time independent, and the I–V from −100 to −60 mV was linear, corresponding to an apparent input resistance of 9.3 ± 1.4 GΩ ( n = 23). The outwardly rectifying current was sensitive to the K+ channel blocking ion tetraethylammonium (TEA), which had a 50% blocking concentration of 0.66 m m (at +50 mV). The 'TEA-sensitive' component of the outwardly rectifying current had time- and membrane potential-dependent properties, activated near −45 mV and was half-activated at −25 mV. The reversal potential of the 'TEA-sensitive' current with external K+ concentration of 5 m m and internal concentration of 145 m m , was −84 mV, indicating that the current was primarily carried by K+ ions. The resting membrane potential of isolated chondrocytes (−38.1 ± 1.4 mV; n = 19) was depolarized by 14.8 ± 0.9 mV by 25 m m TEA, which completely blocked the K+ current of these cells. These data suggest that this voltage-sensitive K+ channel has an important role in regulating the membrane potential of canine articular chondrocytes. 相似文献
140.
Mitchell LE, Risch N. Correlates of genetic risk for non-syndromic cleft lip with or without cleft palate. Clin Genet 1993: 43: 255–260. © Munksgaard, 1993 Multivariate analysis was used to determine which characteristics: sex of the proband, sibling sex, severity of the proband's defect or family history, are the best predictors of recurrence risk among siblings of individuals with non-syndromic cleft lip with or without cleft palate (CL \pm P). Sibling recurrence risks are not significantly related to the sex of the proband. Severity of the proband's defect, classified by the extent of the lip defect (unilateral versus bilateral), was found to be a significant predictor of sibling recurrence, whereas involvement of the palate in the proband's defect was not. A positive family history of clefting (i.e. at least one affected first-degree relative in addition to the proband) and the sex of the sibling were also found to be significant predictors of sibling recurrence. The associations between sibling risk and family history, and sibling risk and bilaterality of the proband's defect appear to be mildly confounded. After adjusting for the effects of family history, the risk to siblings of probands with bilateral lip defects is twice the risk to siblings of probands with unilateral defects (O.R. = 2.00; 95% C.I. 1.25-3.19). A positive family history of clefting increases the risk to siblings by greater than 4-fold (O.R. =4.49; 95% C.I. 2.74-7.35), after adjusting for the extent of the proband's lip defect. These results provide a rational strategy for identifying subsets of the ‘at risk’ population which have markedly different recurrence risks. This information is important for genetic counseling, since it allows for more precise estimation of sibling recurrence risks in individual cases. Furthermore, our findings indicate that the power to detect linkage between a genetic marker or a candidate gene and CL \pm P will increase if the study population is ascertained through individuals with bilcteral clefts of the lip, rather than through individuals with either unilateral or bilateral CL \pm P. 相似文献