The effect of exhaustive exercise on the antioxidant enzyme system in skeletal muscle from calcium-deficient rats

 The aim of the current study was to elucidate the synergism of dietary calcium restriction and exhaustive exercise in the antioxidant enzyme system of rat soleus muscle, and to investigate the involvement of neutrophils in exercise-induced muscle damage. Forty-eight male Wistar rats were assigned to the following groups: control (C) or calcium-restricted [1 month (1 M) or 3 months (3 M)]. Each group was subdivided into acutely exercised or non-exercised groups. Soleus muscle from each rat was analysed to determine the levels of antioxidant enzymes [Mn-superoxide dismutase (SOD), Cu,Zn-SOD, glutathione peroxidase (GPX), and catalase (CAT)]. Dietary calcium restriction resulted in calcium deficiency and upregulated the antioxidant enzymes examined except GPX. Conversely, exhaustive exercise significantly decreased GPX and CAT, but not SODs activities in the calcium-restricted (1 M and/or 3 M) rats. Contents of immunoreactive Mn-SOD and Cu,Zn-SOD were only increased in the 3 M rats. During calcium restriction, the mRNA expression of both forms of SOD showed initial upregulation, followed by downregulation. Exhaustive exercise significantly increased the mRNA expressions only in the 3 M rats. Moreover, exhaustive exercise markedly increased myeloperoxidase activity in soleus muscles from the 1 M and 3 M rats compared with the C rats, and significantly enhanced the ability of neutrophils to generate superoxide in the 3 M rats. The results demonstrate that dietary calcium restriction upregulates certain antioxidant enzyme activities in rat soleus muscle, indicating an enhanced resistance to potential increases in intracellular reactive oxygen species. The results also suggest that exhaustive exercise may cause oxidative damage in soleus muscle of calcium-deficient rats through the activation of neutrophils. Received: 4 August 1997 / Received after revision: 29 September 1997 / Accepted: 26 November 1997     

Localization of dopamine-1 receptors along the microdissected rat nephron

Dopamine exerts numerous actions on the kidney but the precise location of its receptor subtypes along the nephron is unknown. Using a microassay we determined the specific binding of ¹²⁵I-Sch 23982, a specific and selective dopamine-1 (DA₁) receptor antagonist, to microdissected glomeruli and tubule segments. Binding of ¹²⁵I-Sch 23982 in the proximal convoluted tubule (PCT) was timeand concentration dependent, saturable and reversible. The linear Scatchard plot of saturation experiments suggested binding to a single site with an apparent K _d of 16.7 nM and B _max of 0.4 fmol·mm^–1 in the PCT, and 6.2 nM and 0.1 fmol·mm^–1 in the cortical collecting tubule (CCT). Mapping of DA₁ binding sites along the nephron revealed their presence in each of the segments examined, albeit in markedly different concentrations: the highest specific binding was measured in PCT followed by the pars recta. Binding was less in the distal nephron, and least in the medullary and cortical thick ascending limb. Modest binding was also detected in glomeruli. In cortical collecting tubules competition studies with unlabeled dopamine and probes for DA₁ (Sch 23390, fenoldopam), DA₂ (domperidone, S-sulpiride), serotonergic (serotonin, ketanserin, mianserin), and -(phentolamine) and -(propranolol) adrenergic receptors indicated a rank-order potency for displacement of ¹²⁵I-Sch 23982 binding, consistent with labeling of DA₁ receptors. Dopamine inhibited Na/K-ATPase both in PCT and CCT, an effect duplicated in the latter segment by the DA₁ agonist fenoldopam, and blocked by the DA₁ antagonist Sch 23390. These results demonstrate specific DA₁ binding sites in a nonhomogeneous pattern along the entire nephron, and suggest that dopamine may exert its effect on Na transport in distal as well as in proximal nephron segments.     

Tetrodotoxin-sensitive persistent current boosts the depolarization of retinal amacrine cells in goldfish

This study aims to resolve a paradox. Experiments measuring alpha band power report an event related decrease (desynchronization) in alpha activity, whereas those measuring evoked alpha report synchronization. During a recognition memory task with human subjects, we measured the evoked (phase locked) and induced (not phase locked) alpha response. The findings reveal that evoked alpha is due to a transient phase locking (at about 100-200 ms poststimulus) of three alpha sub-bands which can be observed only at parieto-occipital sites. In contrast, induced alpha shows a widespread pattern of desynchronization at most recording sites. Thus, opposite alpha responses occur within similar time windows. Evoked alpha synchronization may reflect cortical inhibition which serves to increase the signal to noise ratio for activation processes following immediately later.     

Production of CA125 by human lung cancer cell lines

CA125, which until recently was considered an ovary specific tumor marker, is elevated in the serum of patients with many pathological conditions, including lung cancer. In order to investigate the production of CA125 by human lung cancer cell lines, cell culture and immunochemical staining were performed in three cell lines. Our results showed the cell surface expression of CA125 in both adenocarcinoma and large cell carcinoma cell lines and the production of CA125 in culture medium. This is considered as evidence for in vitro production of CA125 by human lung cancer, and suggests that CA125 elevation is not only the result of ovarian cancer but may be due to other pathological conditions, including lung cancer.     

Modulation during sleep of the cat trigeminal neurons responding to tooth pulp stimulation

Sleep-induced changes in the trigeminal neuron responses to electrical stimulation of the cat tooth pulp were studied. Two parameters were adopted: One was the evoked spike number at two times the threshold intensity (2 X T response magnitude), which would reveal the level shifting of the neuronal response by the sleep-regulatory system. Another was the rate of change in the response intensity when the stimulus was raised to a level of 0.7 time the arousal threshold during light slow wave sleep (sensitivity gradient), which would reflect the influences of the pain-modulatory system driven by strong noxious inputs. It was found that during sleep the two indexes tended to show a correlated change; the neurons which came to have a greater 2 X T response magnitude tended to have a smaller sensitivity gradient than during wakefulness, and vice versa. It was suggested that two contrasting populations of tooth pulp neurons might be differentiated, and that the sleep-regulatory system and the pain-modulatory system would have differential but correlated controls over these two kinds of neurons.     

Properties and localization of the anterior semicircular canal-activated vestibulocollic neurons in the cat

Summary Unit activites of secondary vestibular neurons that selectively responded to stimulation of the anterior semicircular canal nerve (ACN) were recorded extracellularly in the anesthetized cat. Axonal pathways and projections in the spinal cord of the ACN-activated neurons were examined by recording their antidromic responses to stimulation of the lateral and medial vestibulospinal tracts (LVST and MVST), and the bilateral neck extensor motoneuron pools in the C₁segment (C₁dorsal rami [DR] motoneuron pools). In order to determine whether the neurons had ascending axon collaterals to the extraocular motoneurons, the contralateral (c-) inferior oblique (IO) motoneuron pool was also stimulated. Twenty-seven neurons sent their axons to the ipsilateral (i-) C₁DR motoneuron pool via the LVST without any projection to the extraocular motoneuron pool. All the cells except one were located in the ventral part of the lateral vestibular nucleus. This pathway produced monosynaptic EPSPs with short time-to-peak and short half-width in C₁DR motoneurons (16/16 motoneurons). Eight neurons sent axons to the i-C₁DR motoneuron pool via the MVST without any to the extraocular motoneuron pool. Cell somata were located in the descending nucleus or in the ventral part of the lateral nucleus. These neurons did not produce postsynaptic potentials (PSPs) in any C₁DR motoneurons. All thirty-five neurons sending axons to the c-C₁DR motoneuron pool have ascending axon collaterals to the c-IO motoneuron pool.     

Multiple epithelial cysts of the spleen and on the splenic capsule, and high serum levels of CA19-9, CA125 and soluble IL-2 receptor

An 18-year-old woman with abdominal pain was diagnosed as having splenic cysts by computed tomography scan. She had high serum levels of CA19-9 (2886.8 U/mL; normal value, <35 U/mL), CA125 (131.1 U/mL; normal value, <35 U/mL) and soluble IL-2 receptor (1490 U/mL; normal range, 220-530 U/mL). The resected spleen weighed 1050 g, was 14 x 28 cm, and had more than 10 macroscopic cysts up to 10.3 x 9.5 cm. There were numerous microscopic cysts in the spleen and several on the splenic capsule. The levels of CA19-9 and CA125 in the cyst fluid were 2165550 U/mL and 160400 U/mL, respectively. After the surgery, the serum levels of the tumor markers decreased gradually. The inside of the largest cyst was mainly covered by granulation tissue with a focal lining of epithelial cells, and the other macroscopic cysts had stratified squamous epithelium. The microscopic splenic cysts and cysts on the splenic capsule were lined by either attenuated single-layered or multilayered epithelial cells. The lining epithelial cells of these cysts were positive for epithelial membrane antigen and cytokeratins. CA19-9 and CA125 were detected in the lining cells of the splenic cysts. In the present case, it is suspected that the splenic cysts were derived from the capsular lining cells that showed migration from the capsule or formed microcysts on the splenic capsule, as in the case of ovarian inclusion cysts.