Biomedical subjects

C Murariu

Publications and source records attributed to C Murariu.

4 recordsLinked to original sources

PubMed1999

Role of nitric oxide in hypoxic hypometabolism in rats.

Because it has been recently suggested that nitric oxide (NO) may mediate the effects of hypoxia on body temperature and ventilation, the present study was designed to assess more completely the effects of a neuronal NO synthase inhibitor (7-nitroindazole, 25 mg/kg ip), at ambient temperature of 26 and 15 degrees C, on the ventilatory (V), metabolic (O(2) consumption), and thermal changes (colonic and tail temperatures) induced by ambient hypoxia (fractional inspired O(2) of 11%) or CO hypoxia (fractional inspired CO of 0.07%) in intact, unanesthetized adult rats. At both ambient temperatures, 7-nitroindazole decreased oxygen consumption, colonic temperature, and V in normoxia. The drug reduced ambient or CO hypoxia-induced hypometabolism and ventilatory response, but the hypothermia persisted. It is concluded that NO arising from neural NO synthase plays an important role in the control of metabolism and V in normoxia. As well, it mediates, in part, the hypometabolic and the ventilatory response to hypoxia. The results are consistent with the notion that central nervous system hypoxia resets the thermoregulatory set point by decreasing brain NO.

Animals↗

PubMed1998

Neuromodulators and hypoxic hypothermia in the rat.

This study was designed to assess if opioids or adenosine are involved in the hypometabolism induced by hypoxia in the rat. Accordingly, antagonists such as naloxone (NLX) for opioids or theophylline (THEO) for adenosine were injected into conscious adult rats acutely exposed to either ambient hypoxia (AHx, FIO2: 12%) at ambient temperatures of 26 or 9 degrees C, or to CO hypoxia (COHx, FICO = 0.05%) at an ambient temperature (Ta) of 9 degrees C. Oxygen consumption, ventilation, colonic temperature and shivering were recorded. The results show that with NLX, the degree of hypoxic hypometabolism was reduced with AHx at 26 degrees C and slightly decreased with COHx at 9 degrees C. With THEO, hypoxic hypometabolism was slightly reduced with AHx and COHx at 9 degrees C. The ventilatory response to AHx and COHx was not consistently affected by either NLX or THEO. It is concluded that adenosine and opioids play a minor role, in mediating AHx or COHx hypothermia, especially during cold exposure.

Adenosine↗

PubMed1998

Exercise limitation in obstructive lung disease.

OBJECTIVE: To study the relationship of resting pulmonary function to maximal exercise power output (Wmax) in obstructive lung disease (OLD). SETTING: University Hospital Pulmonary Function Laboratory. SUBJECTS: Twenty-five patients with OLD (6 with asthma and 19 with COPD). METHODS: Measurement of pulmonary lung function, resting arterial blood gases, and maximal symptom-limited exercise on a cycle ergometer. RESULTS AND CONCLUSIONS: In OLD, the only significant contributor to Wmax was the inspiratory capacity (r2 = 0.66; p < 0.001).

Blood Gas Analysis↗

PubMed1997

Ventilatory and metabolic responses to ambient hypoxia or hypercapnia in rats exposed to CO hypoxia.

We have investigated at ambient temperatures (Tam) of 25 and 5 degrees C the effects of ambient hypoxia (Hxam; fractional inspired O2 = 0.14) and hypercapnia (fractional inspired CO2 = 0.04) on ventilation (V), O2 uptake (VO2), and colonic temperature (Tc) in 12 conscious rats before and after carotid body denervation (CBD). The rats were concomitantly exposed to CO hypoxia (HxCO; fractional inspired CO = 0.03-0.05%), which decreases arterial O2 saturation by approximately 25-40%. The results demonstrate the following. 1) At Tam of 5 degrees C, in both intact and CBD rats, V/VO2 is larger when Hxam or CO2 is associated with HxCO than with normoxia. At Tam of 25 degrees C, this is also the case except for CO2 in CBD rats. 2) At Tam of 5 degrees C, the changes in VO2 and Tc seem to result from additive effects of the separate changes induced by Hxam, CO2, and HxCO. It is concluded that, in conscious rats, central hypoxia does not depress respiratory activity. On the contrary, particularly when VO2 is augmented during a cold stress, both V/VO2 during HxCO and the ventilatory responses to Hxam and CO2 are increased. The mechanisms involved in this relative hyperventilation are likely to involve diencephalic integrative structures.

Animals↗