Search PubMed⌕ Search

Biomedical subjects

R Pascual

Publications and source records attributed to R Pascual.

64 records · Page 4Linked to original sources
PubMed1980

Origin of guinea-pig plasma dopamine beta-hydroxylase.

1 Exposure of guinea-pigs to a CO2-enriched atmosphere (20% CO2, 25% O2, 55% N2) for 1 to 5 h caused a marked, progressive increase of plasma dopamine beta-hydroxylase (DBH) activity which reached its peak after 2 h of CO2 exposure and then gradually decreased. The increase was abolished by mecamylamine administration before exposure in CO2. Plasma levels of noradrenaline (NA) also increased after CO2 exposure. 2 Guanethidine administration, before exposure to CO2, abolished the increase of plasma NA but potentiated the increase of circulating DBH. Phenoxybenzamine injection, before exposure to CO2, also potentiated the increase of plasma enzyme activity. In both cases, DBH activity was increased to almost 10 times the basal circulating enzyme levels. 3 Injection of 6-hydroxydopamine (6-OHDA) caused a pronounced decrease of DBH activity in the right atrium, thoracic aorta and spleen; the adrenal enzyme activity was unchanged. Exposure to CO2 of 6-OHDA-treated animals still evoked a dramatic increase of plasma DBH activity comparable to that found in control animals. 4 The increase of plasma DBH activity evoked by exposure to CO2 of adrenalectomized animals was considerably diminished. 5 These data suggest that in the guinea-pig, the adrenal is the main source of the increase of circulating DBH activity evoked by exposure of the animals to a CO2-enriched gas mixture.

Adrenalectomy↗
PubMed1979

Variation in contractile response characteristics of rabbit aorta strips with surface of drug entry.

Contractile responses of rabbit aorta strips to norepinephrine in the presence of cocaine, histamine and serotonin entering through the intima have been compared with those when these drugs enter via the adventitia. The responses to entry through the inner compared with the outer surface occur after a shorter latency, rise at a greater initial velocity and reach a high steady state. Differences persist after removal of the tunica adventitia. Responses of strips to intimal entry appear identical to those of the intact strip. These results suggest an asymmetry of vascular smooth muscle cell characteristics across the thickness of the tunica media of the rabbit thoracic aorta.

Animals↗
PubMed1978

Release of noradrenaline from cat spleen slices by potassium.

1 When cat spleen slices were exposed to a potassium-enriched (140 mM) Krebs solution, 367 +/- 31 ng g-1 5 min-1 of noradrenaline (NA) was released into the bathing medium. 2 Phenylephrine and clonidine (10(-7) to 10(-3) M) did not significantly modify the potassium-evoked NA release; acetylcholine decreased it in a dose-dependent manner. 3 Phenoxybenzamine increased NA release by 50% but phentolamine did not alter it; high concentrations of this drug greatly decreased NA release. Cocaine increased the NA release by about 30%. 4 It is suggested that the failure of sympathomimetic amines to depress, and of alpha-adrenoceptor blocking agents to enhance the release of NA by high potassium concentrations may be related to prolonged depolarization of the nerve terminals, which may desensitize presynaptic alpha-receptors. The fact that the same drugs are able to modify NA release during electrical nerve stimulation may be ascribed to the much shorter periods of depolarization occurring under these conditions.

Acetylcholine↗
PubMed1977

Release of noradrenaline by the ionophore X537A from normal and reserpinized guinea-pig atrium.

The effects of ionophore X537A on the release of 3H-noradrenaline and its metabolites from the superfused guinea-pig left atrium were investigated. Concentrations of ionophore of 10 and 30 mocrometer greatly increased the release of tritium. Of the total increase in radioactivity elicited by X537A 44% was accounted for as noradrenaline and 50% was due to deaminated metabolites. The ionophore-evoked release of tritium was independent of the extracellular calcium ions and was not affected by agents which modify calcium movements such as verapamil, ryanodine, ruthenium red and tetracaine. X537A released 3H-noradrenaline from extragranular sites in MAO-inhibited atria from reserpine-treated animals and this release was also calcium independent. It is concluded that the ability of X537A to release noradrenaline from vesicular or cytoplasmic sites is not related to its ability to couple with and transport calcium ions through membranes. The ionophore might modify the ionic distribution outside and inside the neuronal membrane which would lead to leakage of the transmitter.

Animals↗
PubMedDate not supplied

A preliminary study of the reliability of immediate vs. delayed interviews of cardiac arrest witnesses.

INTRODUCTION: Methods to characterize the interval between a collapse from cardiac arrest until a 911 call is made have not yet been developed. OBJECTIVE: To determine the concordance of cardiac arrest data obtained by two methods: an immediate nurse interview of out-of-hospital cardiac arrest (OHCA) witnesses, and a follow-up phone interview performed two weeks later. METHODS: This was a prospective study of OHCA witnesses dating from January 1997 to May 1998. Witnesses were briefly interviewed at the time of emergency department presentation, and two weeks later a more lengthy structured phone interview was performed. The authors identified key data elements: 1) was the arrest witnessed? (Wit); 2) was CPR administered prior to EMS arrival? (BCPR); 3) was the first call placed to 911? (c911); and 4) was the estimated collapse to call interval <4 minutes? (ECCI). The analysis utilized Cohen's kappa statistic and Spearman's correlation coefficient. RESULTS: A convenience sample of 42 matched pairs of OHCA cases was analyzed. Kappa statistics for agreement between methods were: 1) Wit(kappa = 0.750), 2) BCPR(kappa = 0.892), 3) c911 (kappa = 0.892), and 4) ECCI(kappa = 0.571, Spearman's 0.528). CONCLUSION: There is good to excellent agreement between immediate and phone interview data retrieval methods. Phone interviews appear to yield data comparable to that with the more difficult and expensive, direct interview method.

Aged↗