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Biomedical subjects

J L Pannier

Publications and source records attributed to J L Pannier.

60 records · Page 4Linked to original sources
PubMedDate not supplied

Cerebral blood flow in cats after an acute hypertensive insult with damage to the blood-brain barrier.

Cerebral blood flow was measured with the 133Xenon clearance method in anesthetized cats under controlled ventilation. An acute pressure increase in the carotid system increases the cerebrovascular permeability to Evans blue, indicating damage to the blood-brain barrier. In these conditions the reactivity or cerebral blood vessels toward changes in the acid-base balance is altered: the CO2 reactivity is less pronounced, while the effect of increasing the plasma (HCO-3) is more pronounced than in normal cats. Autoregulatory capacity toward moderate alterations in arterial blood pressure or in intracranial pressure is well maintained in these conditions.

Acid-Base Equilibrium↗
PubMedDate not supplied

Effect of non-respiratory alkalosis on brain tissue and cerebral blood flow in rats with damaged blood-brain barrier.

Acute alterations in plasma bicarbonate concentration have minimal effects on intracerebral pH and cerebral blood flow, perhaps due to blood-brain barrier mechanisms. To test this hypothesis, the consequences of an acute rise in the plasma bicarbonate concentration were studied in anesthetized rats previously subjected to an acute pressure pulse in the carotid system with unilateral damage to the blood-brain barrier. In rats subjected to a "heavy" hypertensive insult, the hemisphere on the side of the lesion showed a lactic acidosis, edema, and a depression of cerebral blood flow. An increase in the plasma bicarbonate concentrations of 15--20 mEq/1 during 35 minutes provoked a marked rise in the total CO2 content of this hemisphere, and a further increase in the lactate concentration, but did not later the brain edema nor affect further the already very low cerebral blood flow. An increase in the lactate concentration and a decrease of cerebral blood flow in the "reference" hemisphere indicated that the lesion was not completely unilateral. In rats subjected to a "moderate" hypertensive insult the changes were less pronounced and statistically not significant for all the parameters. There results illustrate the importance of an intact blood-brain barrier for the maintenance of intracerebral pH in the face of acute alterations in plasma [HCO3]. The impaired cerebral blood flow after an acute hypertensive insult did not appear to be influenced by the intracerebral [HCO3].

Alkalosis↗
PubMedDate not supplied

Effect of adrenergic receptor blockade on plasma testosterone response to exercise in conscious dogs.

The aim of this study was 1) to establish the relationship between testosterone (T) levels and the intensity and duration of exercise in conscious dogs, and 2) to investigate the involvement of the sympathetic system in the response of plasma T to acute exercise. The experiments were performed on 14 male mongrel dogs (20-25 kg) trained to run on a motor driven treadmill. Testosterone (T), cortisol, epinephrine, norepinephrine, lactate and haematocrit were measured in arterial blood samples. A brief intensive exercise (leading to exhaustion within 5 or 20 min) induced a marked increase in plasma T, while during more prolonged (60 min) exercise plasma T showed an initial increase followed by a secondary decrease. Blockade of the beta adrenergic receptors with propranolol (Inderal 0.5 mg/kg i.v.) did not modify the changes of plasma T during exercise, but blockade of alpha adrenergic receptors with phentolamine (Regitine 0.5 mg/kg) lowered the exercise induced rise in plasma T.

Animals↗