Analysis of hemodynamic and respiratory effects of PGI2 in the pig

Cardiovascular and pulmonary effects of prostacyclin (PGI2) were investigated in the anaesthetized pig before and after vagosympathectomy at 1',2',3',4',5',10',15' and 20' after the beginning of the infusion. The animals were perfused with PGI2,2ug/kg/min for 4 min. We measured the following parameters : mean arterial pressure, heart rate, cardiac output, stroke volume, mean pulmonary arterial pressure, mean wedge pressure, left stroke work, total systemic resistance, total pulmonary resistance, tidal volume, respiratory frequency, minute volume, lung resistance and compliance, end-tidal CO2, transpulmonary pressure. Our findings suggest that the hypotension observed is due to a reduction in total peripheral resistance by a direct effect of PGI2 on the vascular bed without inhibition of the sympathetic nervous system. Prostacyclin does not directly modify cardiac function and produces a decrease in preload by venous dilation. The changes in pattern of breathing are related to the hypotensive effect of PGI2.

[Respiratory effects of PGI-2 in the pig]

In anaesthetised pig the intravenous perfusion of 2 micrograms/Kg/min/4 min of PGI2 induces within 30'' respiratory changes that spontaneously disappear after perfusion. The PGI2 induces a decrease of respiratory frequency while total pulmonary resistance increases significantly. This changes of pattern of breathing are correlated to tonus of vagus nerve and after vagosimpathectomy are not present. The relationship of tidal volume/frequency has been evaluated according to the blood pressure variation.

[Hemodynamics in swine treated with PGI 2]

The hemodynamic response of pig perfused by PGI2 (2 micrograms/kg/mm/4 min) has been studied before and after vagosympathectomy. Prostacyclin produces hypotension, which depends to an reduction of total peripheral resistances, without cardiac involvement. A venous dilatation is also present with reduction of preload and of systolic volume. The authors conclude assessing that prostaciclyn act by peripheral mechanism.

Plasma turnover and excretion of K-strophanthoside-3H in human volunteers after parenteral administration

Pharmacokinetic parameters of K-strophanthoside-3H, a short-acting cardiac glycoside, were investigated in healthy subjects, patients suffering from heart disease, renal failure and in cholecystectomized patients with a biliary T-tube inserted surgically, after parenteral administration of 250 mug of the glycoside. The healthy subjects, patients suffering from heart disease and those with the biliary T-tube showed a dominant half-time for plasma turnover of the glycoside of 15-16 h after the i.v. route and 18-22 h after the i.m. route and cumulative urinary excretion of the drug over a 24 h period of 37-42% (i.v. route) and 32-33% (i.m. route). The volumes of distribution were lower in patients with heart disease and patients with biliary fistula than in the healthy subjects. In patients suffering from renal failure the dominant half-time of plasma turnover was higher (33 h), while cumulative urinary excretion of the glycoside (12%) and the volumes of distribution were lower than in the healthy subjects. A peak of plasma levels 30 min after i.m. administration of K-strophanthoside-3H leads to the conclusion that this glycoside is rapidly absorbed when injected intramuscularly.