Effect of nerve stimulation on rat skeletal muscle. A study of plasma membrane

Summary The gastrocnemius muscle of the rat showed no morphological, histometric or plasma membrane changes, after sciatic nerve stimulation with a 5 mA current for 30 to 60 min, 10 mA for 30 min and 15 mA for 5 min. However, 10 mA for 60 and 200 min gave rise to mitochondrial and plasma membrane abnormalities. These changes were absent after a rest period. The results indicated the sciatic nerve stimulation at 10 mA for 60 and 200 min caused reversible changes in the rat skeletal muscle mitochondria and plasma membrane.     

Effect of nerve stimulation on rat skeletal muscle. A study of plasma membrane

The gastrocnemius muscle of the rat showed no morphological, histometric or plasma membrane changes, after sciatic nerve stimulation with a 5mA current for 30 to 60 min, 10 mA for 30 min and 15 mA for 5 min. However, 10 mA for 60 and 200 min gave rise to mitochondrial and plasma membrane abnormalities. These changes were absent after a rest period. The results indicated that the sciatic nerve stimulation at 10 mA for 60 and 200 min caused reversible changes in the rat skeletal muscle mitochondria and plasma membrane.     

Catalase activity in electrically stimulated muscle

Summary 10 min of electrical stimulation resulted in a significant rise in gastrocnemius catalase activity.     

Changes in the concentration of vasoactive intestinal peptide in intestinal lymph in response to vagal stimulation in the calf

Summary Stimulation of both vagi caused a significant rise in arterial plasma vasoactive intestinal peptide (VIP) concentration in 3–5-week-old calves with cut splanchnic nerves. This was associated with a pronounced rise in the VIP concentration of intestinal lymph showing that vagal stimulation causes release of VIP from splanchnic viscera.Acknowledgment. This work has been supported by grants from the Agricultural Research Council and the Medical Research Council and we are indebted to Dr D.M. Burley (CIBA) for his continued support.     

Zur peripheren sympathikushemmenden Wirkung des Clonidins

Summary The influences of clonidine, tetracaine and procaine on the effects of electrical stimulation of the postganglionic sympathetic cardiac nerves have been compared in the isolated perfused rabbit heart. Much lower concentrations of clonidine than of tetracaine were necessary to antagonize the output of noradrenaline and the rise of frequency and contractility. Procaine even in the highest concentration tested did not inhibit the effects of nerve stimulation. In addition to its known central depression of sympathetic tone, clonidine exerts a specific inhibitory action on postganglionic sympathetic neurons.     

Serotonergic and cholinergic interaction in the regulation of pituitary-adrenal function in rats

It has been proposed that the central serotonergic inputs which modulate pituitary-adrenal secretion are mediated by cholinergic neurons. We have tested this hypothesis in intact rats. Male Sprague-Dawley rats were injected with cholinergic and serotonergic agents which enhanced transmitter function and with receptor blocking agents. Agents were injected, singly and in combination, into both unstressed and stressed animals. Since the response to cholinergic agents might be due to changes to vasopressin release, Brattleboro (vasopressin deficient) rats were also injected with cholinergic agents. The level of plasma corticosterone at 1-h post-injection was determined. Results indicate that the serotonin receptor blockade decreased the stimulatory, cholinergic effect of physostigmine. Cholinergic receptor blockers did not significantly reduce the corticosterone rise induced by 5-hydroxytryptophan. These results do not support the hypothesis of cholinergic mediation of serotonergic input. Nicotinic and muscarinic receptors appeared to exert opposing influences on the system. The nicotinic receptor antagonist was able to block the stimulatory effect of physostigmine. The muscarinic receptor antagonist significantly elevated plasma corticosterone levels. No differences were found in the effect of physostigmine on Brattleboro rats as compared to controls. These data are interpreted as suggesting that 1) the acetylcholine-induced stimulation of pituitary-adrenal function is mediated, in part, by serotonergic neurons; and 2) stimulation of nicotinic receptors is facilitatory whereas stimulation of muscarinic receptors is inhibitory to pituitary-adrenal function.     

The nature of posterior hypothalamic projections to cardiorespiratory centers in the brainstem

Focal electrical stimulation of the midlateral posterior hypothalamus in the rat produces rapid shallow respiration accompanied by a rise in arterial blood pressure. Stimulation of presumably intrinsic neurons only by glutamate induces slower deeper respiration associated with a fall in blood pressure.     

The nature of posterior hypothalamic projections to cardiorespiratory centers in the brainstem

Summary Focal electrical stimulation of the midlateral posterior hypothalamus in the rat produces rapid shallow respiration accompanied by a rise in arterial blood pressure. Stimulation of presumably intrinsic neurons only by glutamate induces slower deeper respiration associated with a fall in blood pressure.     

基于BP神经网络的杭州湾北岸水下地形遥感反演研究

基于BP神经网络模型,利用同一时期的遥感影像和实测杭州湾北岸海图资料,构建了影像灰度值和水深值之间的单隐层BP神经网络模型,用以反演杭州湾北岸水下地形。结果表明,与传统的统计模型比较,所建神经网络模型反演地形的精度达84％。由此可见,基于影像灰度值和水深值建立的BP神经网络模型在反演海岸水下地形方面具有较强的应用价值。     

Die Wasserbestimmung in Zellmaterial vonSaccharomyces cerevisiae nachKarl Fischer

Summary A method for the determination of wet and dry weight, has been developed which is adapted for small quantities of yeast. The wet yeast is prepared by a standardized suction filter method and titrated with Karl-Fischer solution. The dry matter content of yeast cells, harvested at daily intervals from growing cultures, changes in an increasing manner when the cultures becomes older. The values rise from about 20% to more than 30% dry matter from the second to the seventh day respectively.     

Maternal influences on cardiovascular pathophysiology.

Elevated blood pressure (BP) is of special clinical significance because of its association with pathophysiologies such as heart disease, renal failure, and stroke. We described the development of a protocol for use with hypertensive rats in which prepubertal exposure to a high salt (8% NaCl) diet results in a pathophysiological syndrome including rapid increase in BP, failure to maintain normal weight gain, renal damage, cerebrovascular lesions, and early mortality. These phenomena are described for the inbred spontaneously hypertensive rat (SHR), and for reciprocal F1 hybrids of a cross between SHR and the Dahl salt-sensitive (SS/Jr) inbred strain. The study with reciprocal F1s revealed striking effects of maternal environment on pathophysiological response to a high salt diet. F1s nurtured by SHR mothers weighed less at 35 days of age, and after exposure to the high salt diet suffered more rapid BP increases, greater incidence of stroke, body weight loss, and mortality, than F1s nurtured by SS/Jr dams. These results suggest that maternal mediation of the nutritional status of the animal may play an important role in determining susceptibility to elevated BP and subsequent pathophysiology associated with exposure to a high salt diet. The implication of these findings for human hypertension is briefly discussed.     

Piroxicam-induced analgesia: Evidence for a central component which is not opioid mediated

Piroxicam is a nonsteroidal anti-inflammatory drug with a potent analgesic effect. In order to establish whether the analgesic action of Piroxicam has a central component, we studied the effect of the drug on the nociceptive orbicularis oculi reflexes evoked by electrical stimulation of the cornea and supraorbital nerve in healthy subjects. Piroxicam significantly suppressed the corneal reflex and R3 component of the blink reflex by 28% (p<0.05) and 50% (p<0.01), respectively. This effect was not reversed by the i.v. injection of naloxone. Beta-endorphin levels did not change. Piroxicam administration induces distinct inhibitory changes in nociceptive reflexes, which suggests that the analgesic action of the drug has a central component. The ineffectiveness of naloxone, and the lack of beta-endorphin changes, indicate that this central action is independent of the opioid system; other pain regulatory systems are probably involved.     

Piroxicam-induced analgesia: evidence for a central component which is not opioid mediated.

Piroxicam is a nonsteroidal anti-inflammatory drug with a potent analgesic effect. In order to establish whether the analgesic action of Piroxicam has a central component, we studied the effect of the drug on the nociceptive orbicularis oculi reflexes evoked by electrical stimulation of the cornea and supraorbital nerve in healthy subjects. Piroxicam significantly suppressed the corneal reflex and R3 component of the blink reflex by 28% (p < 0.05) and 50% (p < 0.01), respectively. This effect was not reversed by the i.v. injection of naloxone. Beta-endorphin levels did not change. Piroxicam administration induces distinct inhibitory changes in nociceptive reflexes, which suggests that the analgesic action of the drug has a central component. The ineffectiveness of naloxone, and the lack of beta-endorphin changes, indicate that this central action is independent of the opioid system; other pain regulatory systems are probably involved.     

Maternal influences on cardiovascular pathophysiology

Elevated blood pressure (BP) is of special clinical significance because of its association with pathophysiologies such as heart disease, renal failure, and stroke. We described the development of a protocol for use with hypertensive rats in which prepubertal exposure to a high salt (8% NaCl) diet results in a pathophysiological syndrome including rapid increase in BP, failure to maintain normal weight gain, renal damage, cerebrovascular lesions, and early mortality. These phenomena are described for the inbred spontaneously hypertensive rat (SHR), and for reciprocal F₁ hybrids of a cross between SHR and the Dahl salt-sensitive (SS/Jr) inbred strain. The study with reciprocal F₁s revealed striking effects of maternal environment on pathophysiological response to a high salt diet. F₁s nurtured by SHR mothers weighed less at 35 days of age, and after exposure to the high salt diet suffered more rapid BP increases, greater incidence of stroke, body weight loss, and mortality, than F₁s nurtured by SS/Jr dams. These results suggest that maternal mediation of the nutritional status of the animal may play an important role in determining susceptibility to elevated BP and subsequent pathophysiology associated with exposure to a high salt diet. The implication of these findings for human hypertension is briefly discussed.     

基于BP算法的纹理图象合成研究

针对目前纹理图象合成技术存在的弱点,应用人工神经网络BP算法实现了纹理图象的合成。通过对纹理图象的分析和特征提取来获取图象的各种参数信息,然后采用人工神经网络BP算法,建立BP网络模型,将原始图象的特征函数作为BP网络的输入,通过学习-训练,确定该图象的人工神经网络结构,并最终通过程序合成了纹理图象。     

Effects of inhibition and stimulation of Na+-K+ active transport on the resting membrane input conductance of the guinea-pig ventricle

The effects of inhibition by ouabain and stimulation by high frequency drive of the sarcolemmal Na+-K+ active transport system on the resting input conductance (gi) of guinea-pig ventricular muscles were determined. Although both pump inhibition and stimulation were associated with changes in electrophysiological properties of the muscles, neither had a significant effect on gi.     

Electrocardiographic and behavioral effects ofl-DOPA in the guinea-pig

Conclusions The effects ofl-DOPA administered per os on conditioning, spontaneous behavior and the electrocardiogram of the guinea-pig are reported and compared.l-DOPA is able to inhibit the conditioned behavior in doses per os without any effect on spontaneous behavior or motility. Moreoverl-DOPA in doses up to 15 times higher than the average therapeutic daily dose pro kg used in man (TDD), does not alter the ECG of the guinea-pig. We did not observe ECG changes even after a total dose pro kg 60 times higher than TDD, which induced behavioral alterations in the 4 treated animals and one death.The present results may indicate psychotropic properties forl-DOPA and do confirm the low toxicity and cardiotoxicity of the drug, when supplied in a pure preparation of quality 12.

---

Zusammenfassung Verabreicht manl-Dopa (1000 mg/kg per os) an Meerschweinchen, so kann dadurch das konditionierte Verhalten gehemmt werden, während das Spontanverhalten und die Motilität unverändert bleiben. Es sind keine Modifikationen des Elektrokardiogramms festzustellen, selbst dann nicht, wenn die 60fache mittlere therapeutische Tagesdosis gegeben wird.

     

Protein kinase C-dependent NF-κB activation is altered in T cells by chronic stress

Chronic stress has been associated with impaired immune function. In this work we studied the effect of chronic mild stress (CMS) exposure on the early intracellular pathways involved in T cells after stimulation with mitogen. We found that mitogen stimulation of T lymphocytes from CMS-exposed mice resulted in a reduction of the intracellular [Ca²⁺] rise, an impairment of growth-promoting protein kinase C (PKC) activation, a lower NF-κB activation and an increase in the inhibitory cAMP-protein kinase A (PKA) pathway activity with respect to those found in control lymphocytes. However, T cell activation with the direct PKC activator phorbol 12-myristate 13-acetate plus calcium ionophore led to a similar proliferative response in both CMS and control lymphocytes, indicating that signals downstream of PKC would not be affected by stress. In summary, our results show that chronic stress induced an alteration in T cell early transduction signals that result in an impairment of the proliferative response.Received 11 February 2005; received after revision 20 May 2005; accepted 6 June 2005     

Comparative studies on the covalent binding of the carcinogen benzo(a)pyrene to DNA in various model systems.

The covalent binding of tritiated benzo(a)pyrene (BP) to DNA has been determined in rat liver in vivo, in rat liver perfused in situ, after incubation of BP with liver single cells, with liver homogenate, with liver microsomes and DNA, with fibroblasts from a rat granuloma pouch, and with 2 cell lines. Liver single cells were found to be a valuable compromise between the most sensitive system (microsomal incubation of BP and DNA) and the biologically most relevant system (in vivo).     

Ricerche fisiologiche sulla distribuzione periferica del nervo depressore aortico destro nel cane

Summary The periferal distribution of the right aortic nerve has been studied in physiological experiments on the dog. It has been found that after section of both Hering's nerves and left vago-depressor trunk and after denervation of the baroceptor area ofMuratori-Nonidez lying at the root of the right subclavian artery, the electrical stimulation of one splancnic nerve or the intravenous injection of adrenaline still produces a reflex bradycardia; moreover the cooling of the vagus nerve still results in a rise of the blood pressure. It is inferred that a group of baroceptor fibres of the right aortic nerve originate from areas situated in the aortic region.