Coronary vascular and myocardial effects of substance P in hypercholesterolemic rabbits.

Age-matched male New Zealand white rabbits (n = 16) were allocated to two groups: group 1 (n = 8) received a standard rabbit diet; group 2 (n = 8) received a 2% cholesterol-enriched diet. After 8 weeks of prescribed diet, hearts were excised and placed on a constant perfusion pressure Langendorff-type apparatus. Coronary flow, left ventricular pressure, and isovolumic dP/dt were continuously measured. Baseline recordings were made and then a single 5 nmol bolus dose of substance P was delivered into the coronary perfusate. Mean serum cholesterol levels in group 1 were 53 +/- 17 (SEM) mg.dl-1, in group 2 1438 +/- 143 mg.dl-1. In group 1, the injection of substance P caused mean coronary flow to increase 39 +/- 6%, mean coronary vascular resistance to decrease 28 +/- 3%, and mean dP/dt to increase 11 +/- 4%. In group 2, coronary flow increased 57 +/- 13%, coronary vascular resistance decreased 33 +/- 5%, and dP/dt increased 17 +/- 4%. Within groups, values changed significantly from baseline but these changes were not significantly different between groups. The duration of coronary flow response was 113 +/- 20 s in group 1 and 63 +/- 8 s in group 2. Substance P is a potent dilator of coronary resistance vessels and has positive inotropic effects in the rabbit. High levels of cholesterol exposure do not alter the magnitude of substance P-induced vasodilation, but the duration of the response is shortened.

Instantaneous changes in arterial compliance reduce energetic load on left ventricle during systole.

We tested the hypothesis that arterial compliance changes during each cardiac cycle, and that these instantaneous changes are beneficial for energy conservation. Using an adaptive identification procedure, we were able to obtain an instantaneous impulse-response representation of the arterial system. By assuming a three-element windkessel model, we obtained the instantaneous compliance. The arterial compliance remained relatively constant during diastole but increased during systole. The calculated time trajectory was compared with an optimal compliance calculation based on minimum ventricular ejection energy criteria. The two compliance trajectories followed similar paths. We conclude that increases in arterial compliance during systole reduce the energy demands on the left ventricle.

The use of a small intra-aortic balloon to increase coronary flow.

A small spherical balloon, mounted on a catheter, was positioned, via an arteriotomy, in the ascending aorta 1 cm above the aortic valve in 10 dogs. The balloon was inflated for 60 ms, through the equipment of the intra-aortic balloon pump, during various parts of the cardiac cycle. When the inflation occurred during the rapid ejection phase, the systolic component of the coronary flow increased by 32.57 +/- 5.4 per cent (P less than 0.001), resulting in a 6.69 +/- 1.14 per cent (P less than 0.001) increase of the total (effective forward) flow. The tension time index increased by 9.01 +/- 0.85 per cent (P less than 0.001). The left ventricular end-diastolic pressure and indexes of contractility did not change. When the inflation occurred during the reduced ejection phase the increase in coronary flow and tension time index was less. When the inflation occurred during the first third of diastole, there were no significant changes in the pressures and flow. In the middle third of diastole, the inflation of the balloon produced a 6.5 +/- 0.99 per cent (P less than 0.001) increase of the total flow, without significant changes in the pressures, except for a small increase in the mean diastolic aortic pressure. When the inflation occurred in the last third of diastole, the total coronary flow increased by 10.47 +/- 1.06 per cent (P less than 0.001). There was a decrease in the aortic end diastolic pressure and a 1.08 +/- 0.42 per cent (P less than 0.02) increase in the time tension index. In five dogs, additional observations were made using another mode of inflation. The balloon remained inflated during the entire diastolic period. The total coronary flow increased by 17.46 +/- 4.8 per cent (P less than 0.01), along with a small increase in the diastolic aortic pressure. Indexes of contractility did not change. In conclusion, a small spherical balloon functioning as a pump in the ascending aorta, in close proximity to the coronary ostia, can significantly increase the coronary blood flow.

[Development of the breasts of the fetus. Effects of the administration of hormonal preparations during pregnancy]. / Développement des glandes mammaires du foetus. Effet de l'administration des préparations hormonales administrées pendant la grossesse

The mammary glands of ten still-birth premature fetuses were studied histologically. In seven cases a combination of oestrogen-progesterone preparations were administered to the mother in early pregnancy for a duration of at least 3 months. In three cases no hormones were administered. According to our observations and the experimental work of other investigators, we may conclude that oestrogenic hormones inhibit the development of the mammary gland.

Amniocentesis: indications and complications.

Transabdominal amniocentesis is described and our experience with this method is presented. No severe maternal complications were recorded. In two cases accidental puncture of fetal blood vessels in pregnancies over 40 weeks led to delivery by cesarean section. We believe that, although fetal complications are rare, the indications for amniocentesis should be significant enough to discount the hazards of the procedure.