Lukačínová A.,

SUMMARY1. Respiratory neurones of mammals are rhythmically active because their membrane potential fluctuates periodically over a voltage range of -70 to -55 mV. These respiratory drive potentials lead to periodic discharges of bursts of action potentials lasting for 1-2 s. The neuronal processes stabilizing this rhythmic activity involve excitatory and inhibitory synaptic processes that interact with specific membrane properties of the postsynaptic neurones. In the present experiments, performed on dorsal and ventral groups of respiratory neurones under in vivo and in vitro conditions, we verified the modulating feature of such intrinsic neuronal properties.2. Intrinsic neuronal properties involve Ca2" mechanisms that lead to intracellular Ca2' accumulation, and consequently to activation of Ca2+-dependent K+ currents.3. Blockade of intracellular Ca2+ accumulation significantly changed the amplitude and pattern of respiratory drive potentials, and blocked initial hyperpolarizing shifts of the membrane potential following each period of synaptic activation.4. The data demonstrate that postsynaptic activities and action potential discharges activatelow andhighvoltage-activatedCa2+ currentsleadingto intracellular Ca2+ accumulation and to activation of Ca2+-dependent K+ currents that significantly modulate the voltage response of medullary respiratory neurones to on-going synaptic activation. These intrinsic membrane properties also seem to be involved in the processes controlling termination of rhythmic burst discharges.

No abstract

No abstract

The aim of the present investigation was to evaluate the effects of multigenerational (P, F1 and F2) exposure to low doses of lead, mercury and cadmium dissolved in tap water on the reproductive potency of Wistar rats and the physical health of their progeny. The animals were divided into 4 groups - control (C) and 3 groups intoxicated by metals (Pb, 100 μM; Hg, 1 μM; Cd, 20 μM, respectively). Females gave births from the 13th to the 78th week of experiment. Parameters of reprotoxicity such as number of litters, total number of neonates (assigned in the birth day), and number of weanlings (28th day after birth) were measured in 13-week intervals. Our data show an increase of most reproductive parameters in parental generation of rats exposed to lead and mercury and a decrease of reproductive parameters of exposed animals in subsequent F1 and F2 generations. Exposure to cadmium had no significant effect on the reproductive parameters in comparison with the control group.

Agonal gasping provoked by asphyxia can save ~15% of mammals even from untreated ventricular fibrillation (VF), but it fails to revive infants with sudden infant death syndrome (SIDS). Our systematic study of airway reflexes in cats and other animals indicated that in addition to cough, there are two distinct airway reflexes that may contribute to auto-resuscitation. Gasp- and sniff-like spasmodic inspirations (SIs) can be elicited by nasopharyngeal stimulation, strongly activating the brainstem generator for inspiration, which is also involved in the control of gasping. This “aspiration reflex” (AspR) is characterized by SI without subsequent active expiration and can be elicited during agonal gasping, caused by brainstem trans-sections in cats. Stimulation of the larynx can activate the generator for expiration to evoke the expiration reflex (ExpR), manifesting with prompt expiration without preceding inspiration. Stimulation of the oropharynx and lower airways provokes the cough reflex (CR) which results from activating of both generators. The powerful potential of the AspR resembling auto-resuscitation by gasping can influence the control mechanisms of vital functions, mediating reversal of various functional disorders. The AspR in cats interrupted hypoxic apnea, laryngo- and bronchospasm, apneusis and even transient asphyxic coma, and can normalize various hypo- and hyper-functional disorders. Introduction of a nasogastric catheter evoked similar SIs in premature infants and interrupted hiccough attacks in adults. Coughing on demand can prevent anaphylactic shock and resuscitate the pertinent subject. Sniff representing nasal inspiratory pressure and maximal inspiratory and expiratory pressures (MIP and MEP) are voluntary counterparts of airway reflexes, and are useful for diagnosis and therapy of various cardio-respiratory and neuromuscular disorders.

The effects of fl avonoids quercetin (Q) and chrysin (Ch) were evaluated in rats with alloxan-induced diabetes mellitus. A single dose of 60 mg alloxan (A) per kg body weight was injected to rats fasting for at least 16 h. Q or Ch in amounts of 50 and 100 mg/kg body weight were administered orally to the control non-treated and A treated rats (10 rats per group) for 3 days prior and 7 days after A injection. Glycaemia, glycosuria, total antioxidant status (TAS) and activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx) were determined. Both Q and Ch prevented serum glucose elevation due to A, but the effect of Ch was weaker, particularly at the higher dose. The benefi cial effects of fl avonoids on glycosuria and antioxidant status differed between Q and Ch, being generally greater in case of Q, and depended on the dose. It is suggested that the protective effect of fl avonoids under study is partly related to their antioxidative/chelatory properties and partly to the alteration of renal glucose absorption.

No abstract