Search PubMed⌕ Search

Biomedical subjects

A Ungar

Publications and source records attributed to A Ungar.

At least 55 records · Page 3Linked to original sources
PubMed1976

Divergent changes in the rate of development of pressure in the left ventricle and in the performance of the heart as a pump.

Dog hearts were prepared in situ so that heart rate (HR), left ventricular end diastolic pressure (LVEDP) and mean aortic pressure (MAP) could be controlled separately during computation of left ventricular dP/dt max and external stroke work (SW). Progressive increases in HR consistently raised dP/dt max over a wide range, and consistently lowered SW except at low rates. Progressive increases in LVEDP or MAP consistently raised both dP/dt max and SW. Infusion of noradrenaline consistently raided both dP/dt max and SW, except at very high HR when only dP/dt max was consistently raised. Our results lead us to question the validity of equating changes in pre-ejection measurements with changes in performance of the heart as a pump under abnormal conditions and in the assessment of inotropic agents.

Animals↗
PubMed1975

Arterial catecholamines in hypoxic exercise in man.

1. We measured the minute ventilation and arterial blood catecholamine concentrations in four normal men standing and at two levels of moderate treadmill exercise breathing 14% oxygen or air. 2. Minute ventilation was significantly higher during hypoxic exercise than during normoxic exercise at an oxygen uptake of 1500 ml/min. 3. Arterial plasma noradrenaline during hypoxic exercise at an oxygen uptake of 1500 ml/min was significantly greater than at rest. 4. Arterial plasma noradrenaline during normoxic exercise at an oxygen uptake of 1500 ml/min was not elevated above the resting concentration. 5. The results are compatible with the suggestion that increased concentrations of arterial plasma noradrenaline contribute to the hypoxic potentiation of the respiratory response to moderate exercise.

Adult↗
PubMed1974

Cardiovascular actions of prostaglandin C in the cat and dog.

1 Prostaglandin C(2) causes a prolonged fall in arterial blood pressure in the cat.2 At constant heart rate this fall in arterial pressure is accompanied by falls in stroke volume, left ventricular end diastolic pressure, and left ventricular dP/dt max.3 If mean aortic pressure and left ventricular end diastolic pressure are held constant as well as heart rate, prostaglandins C(2) and E(2) do not affect dP/dt max in the cat.4 In the dog, under similarly controlled conditions, prostaglandins C(2) and E(2) raise dP/dt max.5 We conclude that prostaglandins E(2) and C(2) have no direct inotropic action in the cat, but both have a direct positive inotropic action in the dog.

Animals↗
PubMed1971

On the direct and crossed components of reflex responses to unilateral stimulation of the carotid body chemoreceptors in the dog.

1. In dogs under chloralose-urethane anaesthesia the chemoreceptors of the two carotid bodies were separately stimulated.2. The distribution of three primary reflex responses to carotid body stimulation was studied: parasympathetic bradycardia, sympathetic vasoconstriction, and increase in somatic phrenic nerve activity.3. The reflex bradycardia evoked by either carotid body was mediated by both vagus nerves, but when either vagus was blocked a greater response could be obtained from the contralateral than from the ipsilateral carotid body.4. The reflex vasoconstriction evoked by either carotid body was seen in both hind limbs, with no predominance in either limb.5. The reflex increase in phrenic nerve activity evoked by either carotid body was seen in both phrenic nerves, with no predominance in either nerve.

Anesthesia, General↗