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Biomedical subjects

P Neumann

Publications and source records attributed to P Neumann.

148 records · Page 9Linked to original sources
PubMedDate not supplied

Effect of PY 108-068, a new calcium antagonist, on general hemodynamics and regional blood flow in anesthetized cats: a comparison with nifedipine.

The hemodynamic effects of PY 108-068 (PY), a new benzoxadiazolyle dihydropyridine derivative with calcium antagonistic effects on vascular smooth muscle, were investigated in chloralose--urethane-anesthetized open-chest cats. Regional blood flow was measured with tracer microspheres. PY lowered blood pressure and increased cardiac output similarly to nifedipine (N). Unlike the latter drug, PY decreased heart rate without showing evidence of cardiodepression. Right atrial pressure increased slightly less than with N. All these effects were dose dependent in the dose range from 1 to 43 micrograms/kg i.v.. PY and N increased myocardial blood flow to the same extent initially, and redistributed it in favor of the outer layer of the left ventricle. The activity of sublingually administered PY was comparable to that of a similar intravenous dose. An approximately three times larger intraduodenal dose was needed for similar effects. Our results provide preliminary in vivo evidence that it is possible to separate the negative chronotropic from the negative inotropic effects of calcium antagonists.

Anesthesia↗
PubMedDate not supplied

Attitudes that predict antinuclear-war activity in medical students.

The possibility of nuclear war may be the most significant threat to health in the world. Medical practitioners have played, and should continue to play, a leading role in raising awareness of this danger. In the present study, the attitudes that predict a specific antinuclear-war behaviour (that is, signing a letter to the Prime Minister of Australia to request more active political effort to prevent nuclear war) were studied in a group of 143 undergraduate medical students. Attitudes towards that particular behaviour were assessed by means of a questionnaire, and the differences in attitude between students who chose to sign and those who chose not to sign the letter were analysed statistically by means of discriminant analysis. The key differences in attitude between signers and non-signers of the letter was in their belief that such an action would achieve tangible positive outcomes. The results are discussed in terms of the need to target strategies of change for the specific attitudes which are likely to modify behaviour and to promote antinuclear behaviours in medical practitioners, which in turn may alter the behaviour of politicians.

Attitude of Health Personnel↗
PubMedDate not supplied

PN 200-110, a new calcium antagonist: electrophysiological, inotropic, and chronotropic effects on guinea pig myocardial tissue and effects on contraction and calcium uptake of rabbit aorta.

The compound isopropyl 4-(2,1,3- benzoxadiazol -4-yl)-1,4-dihydro-5-methoxycarbonyl-2,6-dim ethyl-3- pyrid inecarboxylate (code name PN 200-110 [PN]) was investigated for calcium antagonistic effects in experiments in vitro. Action potentials recorded with intracellular microelectrodes in guinea pig papillary muscles were changed little by PN, 10(-7) M, except for a slight shortening of the duration of the plateau phase. Slow action potentials elicited in partially depolarized papillary muscles were gradually diminished and finally blocked by this concentration of PN. Contractile force was diminished in normal and partially depolarized muscles. The rate of spontaneously beating guinea pig right atria was decreased dose dependently, and the EC25 was 4.5 x 10(-10) M. The EC25 for the negative inotropic effects measured on paced guinea pig left atria was 1.5 x 10(-8) M. No membrane-stabilizing effects were found. Calcium-induced contraction of rabbit aorta in depolarizing bath solution was inhibited with an apparent pA2 of 10.3. Contraction elicited by graded depolarization at a constant calcium concentration was inhibited with an EC50 of 1.4 x 10(-9) M. Under resting conditions PN did not alter net uptake of 45Ca2+. KCl-stimulated uptake was inhibited with an EC50 of 3.6 x 10(-9) M. Neither noradrenaline-induced contractions nor noradrenaline-stimulated net uptake of 45Ca2+ were inhibited by a concentration of PN as high as 10(-5) M. PN thus is selective on cardiac tissue with respect to negative chronotropic versus inotropic activity and on rabbit aorta with respect to potential-operated versus receptor-operated channels.

Action Potentials↗