Effects of prostaglandins E1 and F1alpha on the heart-lung preparation of the dog

Intra-operative blood pressure control by prostaglandin E1 in patients with hypertension and ischemic heart disease--a multi-center study

The purpose of this multi-center study was to evaluate the efficacy and safety of prostaglandin E1 (PGE1) administration in achieving deliberate hypotension and in treating intraoperative hypertension for patients with a history of hypertension and ischemic heart disease. PGE1 (0.08 microg.kg(-1).min(-1)) decreased systolic blood pressure from 125 +/- 29 to 106 +/- 22 mmHg (mean +/- SD) in the deliberate hypotension group (n = 158) and from 155 +/- 34 to 125 +/- 32 mmHg in the antihypertension group (n = 55). The heart rate significantly increased from 80 +/- 15 to 85 +/- 18 beats.min(-1) in the deliberate hypotension group, but was not significantly altered in the antihypertension group. The time required to obtain the desired level of blood pressure was approximately 20 min in the deliberate hypotension group. When the infusion was stopped, blood pressure returned approximately to the preinfusion level within about 20 min. No rebound hypertension was observed. PGE1 significantly increased the urine flow in patients who had a low urine flow before PGE1 infusion. Thirteen out of 213 patients (5.6%) had side effects such as excessive hypotension (1%), phlebitis (3%), and unexpected tachycardia (1%), which were alleviated gradually after discontinuation of PGE1 infusion. No dysarrhythmia and further ST segment changes in the electrocardiograms were observed. These findings suggest that PGE1 can be safely used to control arterial blood pressure during surgery in patients having preoperative hypertension and ischemic heart disease.

Experimental study of the effect of prostaglandin administration on tooth movement--with particular emphasis on the relationship to the method of PGE1 administration

Recently, the mechanism of action of prostaglandins in promoting bone resorption has received wide attention. Prostaglandins are used in orthodontics to shorten the period of tooth movement. PGE1 was administered locally (5 micrograms/kg every 12 hours) and systemically (7.5 ng/kg/min) to rats to study the difference in the efficacy of the two methods of administration in accelerating bone resorption. The Waldo method was used on 72 Wistar rats (8 weeks old) for 5 days to induce mesial movement of the first molar. The body weight of the rats was measured every 12 hours from the start of the experiment. Tissues were examined in the mesial surface of the mesial root and in the interradicular septum between the linguomesial root and the linguodistal root of the upper first molar. The pressure side of the mesial surface of the mesial root was studied, as well as the pressure side of the interradicular septum. The results showed that decrease in body weight during the experiment was more prominent in the local administration group than in the systemic administration group. In both the group receiving PGE1 through local administration and the group receiving PGE1 through systemic administration, the numbers of osteoclasts and Howship's lacunae were markedly increased over those in the control groups. Moreover, compared with local administration, systemic administration of PGE1 had a more marked effect on bone resorption.

Inhibition by thiamine tetrahydrofurfuryl disulfide (TTFD) of the arachidonic acid cascade-line activation as evidenced in the heart-lung preparation of the dog

The effects of thiamine tetrahydrofurfuryl disulfide (TTFD) on the gradual increase in the coronary blood flow (CBF) inherent in the canine heart-lung preparation were studied. TTFD is a disulfide-type derivative of thiamine reported to have an antiinflammatory effect in experimental animals. Since it was found that the substance could reverse the gradual increase in CBF, the possibility that the reversal was brought about through an inhibition of activation of the arachidonic acid cascade-line was tested, examining the effects of this substance on the CBF increase produced by arachidonic acid (AA) and prostacyclin (PGI2). The vasodilator response to AA, which was barely detectable at the start of the experiment at which CBF was at a physiological low level, became potentiated as the gradual increase in CBF occurred, returning to the initial magnitude after TTFD, while the vasodilator response to PGI2 remained essentially unchanged during the entire course of the experiment. It was concluded that TTFD reversed the gradual increase in CBF in the HLP through the inhibition of the arachidonic acid cascade-line activation.

Enhanced responsiveness of the coronary blood vessel of the dog heart-lung preparation to PGI2 after chronic chemical sympathectomy

Chronic chemical denervation of the sympathetic nervous system with 6-OH dopamine resulted in an augmentation of the coronary blood flow (CBF) increase inherent in the canine heart-lung preparation, but not in an augmented accumulation of 6-keto PGF1 alpha in the circulating blood. In denervated HLP, 6-keto PGF1 alpha was lower and the vasodilator response to PGI2 larger at the start of the experiments. It was concluded that exaggerated increase in CBF was due to a potentiation of the vasodilator response to PGI2.

Studies on experimental immune complex nephritis (3). Therapeutic effect of prostaglandin E1 alpha-cyclodextrin host molecule (PGE1 . CD) on serum sickness nephritis in rats

The effect of prostaglandin E1 alpha-cyclodextrin host molecule (PGE1 . CD) was estimated by using a model of immune complex glomerulonephritis induced in rats by i.v. injection of 1 mg of rabbit serum albumin every other day. PGE1 . CD was given subcutaneously for 10 days after nephritis was definitely induced and resulted in a rapid restoration of various biochemical parameters, especially in plasma. The continuous s.c. administration of PGE1 . CD (300 micrograms/rat/day) with a mini osmotic pump provoked a therapeutic effect similar to that obtained with twice daily s.c. administration of PGE1 . CD (300 micrograms/rat X 2/day). Both PGE1 . CD groups revealed less glomerular damage and fewer locations of immune complexes in glomeruli as demonstrated by light and immunofluorescence microscopy. The beneficial effect of PGE1 . CD may be associated with reduced immune complex deposits in glomeruli. The present studies suggest that PGE1 . CD may enhance the clearance of immune complex deposits from the glomeruli rather than inhibiting the formation of immune complex in the circulation.

Effects of prostaglandin E1 on the positive inotropic actions of noradrenaline, nerve stimulation and calcium in the isolated blood-perfused papillary muscle of the dog

The effects of PGE1 on the dog heart were studied using the blood-perfused sinus node and papillary muscle preparations isolated separately from the same animal. PGE1 administered into the papillary muscle artery as bolus injections in doses of 1-1000 ng caused a dose-dependent increase of the developed tension and dT/dt of the papillary muscle. The effect was not inhibited by the beta-adrenoceptor blocking agent pindolol. PGE1 injected into the sinus node artery in doses of 3-300 ng did not change the rate of contraction of the sinus node preparation. PGE1 in the blood concentrations of 4.4 X 10(-9) to 1.7 X 10(-7) M enhanced the positive inotropic responses to noradrenalin and field stimulation as well as to calcium. The influence of PGE1 on the positive inotropic effect of perivascular nerve stimulation was not consistent: the action of perivascular nerve stimulation was enhanced by PGE1 in the majority of preparations but was reduced in one third of preparations. PGE1 in the same blood concentrations as used in the papillary muscle significantly depressed the positive chronotropic responses to noradrenaline and dopamine. The present results indicate that PGE1 induces multiple actions on the dog heart. Its predominant effect on the ventricular myocardium appears to be enhancement of the adrenergic stimuli probably via the facilitation of calcium movement through the myocardial cell membrane. In addition, PGE1 may decrease the sensitivity of beta-adrenoceptors to adrenergic stimuli in the sinus node.

Coronary vasodilatation and adrenergic receptors in the dog heart and coronary

The question of whether the coronary blood vessels contain an intrinsic adrenergic mechanism for vasodilatation of physiological significance has been examined in the canine heart-lung preparation with a donor by studying the response of the coronary vessels to epinephrine, norepinephrine, isoproterenol and salbutamol in combination with practolol. To differentiate the vasodilatation mediated through adrenoceptors in the coronary vessels from that resulting from an increase in the myocardial O2 consumption, a special method of analysis was developed based on the linear relation between the coronary flow and the myocardial O2 consumption. It was found that all four compounds produced an increase in the coronary flow attributable to an increased myocardial O2 consumption. Epinephrine and norepinephrine produced a decrease in the coronary flow after practolol which completely abolished the increase in the myocardial O2 consumption as well as the positive inotropic and chronotropic effects produced by these compounds, while isoproterenol and salbutamol produced an increase. These results indicate that adrenergic beta-receptor exists in the coronary subserving a vasodilatation. However, the vasodilatation through this mechanism is of minor importance under physiological conditions and becomes completely masked in the presence of an overwhelmingly strong vasodilatation consequent to an increase in the myocardial O2 consumption.