Adipocyte morphology during hormone-induced lipid deposition and mobilization. An ultrastructural investigation in the perfused cardiac fat.

The rat pericoronary adipose tissue was perfused in the presence of either the liposynthetic hormone insulin or the lipolytic hormone noradrenaline. Insulin perfusion associated with a) larger adipocyte mean sectional diameter in comparison with noradrenaline perfusion; b) glycogen deposition; c) appearance of small fat globules at discrete sites at the periphery of the main lipid drop. The two latter phenomena were apparently dose-dependent.

Short term effects of intra-arterial propionyl-L-carnitine on isolated canine hind-limbs.

Treatment with propionyl-L-carnitine has been shown to increase the walking capacity of patients with peripheral vascular disease, but the mechanisms responsible for the effect are unknown. To study the effects of propionyl-L-carnitine on musculocutaneous vascular beds and the related mechanisms, a preparation of constant-pressure blood-perfused dog hind-limb was used. Since the propionyl-L-carnitine solution had a pH less than 4 the contralateral limb simultaneously received acidified saline.

Biochemical and morphological changes in isolated rabbit hearts after prolonged hypothermic ischaemia: comparison of two cardioplegic solutions.

This work evaluates the myocardial protective potential of potassium cardioplegia on ischaemically arrested and reperfused hearts by two cardioplegic solutions: the University of Wisconsin solution (UW) and the standard crystalloid solution of St. Thomas' Hospital (ST). Evaluation of myocardial preservation was based on creatine kinase and lactate releases and on high-energy phosphate preservation of isolated rabbit hearts after 4 hours' hypothermic ischaemia.

Vascular resistance and arterial pressure low-frequency oscillations in the anesthetized dog.

The spontaneous variability of heart rate and arterial blood pressure was investigated in chloralose-anesthetized dogs with the left iliac vascular bed mechanically uncoupled from the central circulation. Electrocardiogram, mean arterial pressure (ABP), iliac perfusion and venous pressures, and flow (FLOW) were recorded for 5 min in steady state. Autoregressive spectral and cross-spectral analyses and digital filtering were performed.

Usefulness and limitations of the positive protosystolic peak of coronary arterial blood flow as an index of epicardial arterial compliance.

The aim of the study was to investigate the physiological meaning of the positive peak which appears at the onset of ventricular ejection on traces of blood flow in the left coronary artery. It was proposed that the protosystolic peak could represent systolic charging of epicardial coronary arterial compliance, i.e.

Preservation of rabbit hearts with different cardioplegic solutions at low temperature.

An organ-preserving solution, including in its composition also organic molecules, prepared at the University of Wisconsin (UW), has been successfully used for preservation of liver, pancreas and kidney, and has recently been tested for long-term storage of isolated hearts. We have compared the effectiveness of the UW solution with that of a standard crystalloid cardioplegic solution (St. Thomas, ST) in the functional and structural preservation of isolated hearts.

Peripheral blood flows during colorectal distension in anaesthetised dogs.

Distension of the descending colon elicits reflex cardiovascular responses, including increases in heart rate and arterial blood pressure. To study the relative contribution of vasoconstriction in individual vascular beds to this reflex response, experiments were performed on seven dogs anaesthetised with chloralose and instrumented with electromagnetic flowmeters around the superior mesenteric, the left renal and the left external iliac arteries. The colorectal portion of the intestine was distended at constant pressure (36.

Protective effect of selenium in cardiac ischemia and reperfusion.

The purpose of the present investigation was to establish whether pretreatment with selenium enhances the stores of selenium-dependent glutathione peroxidase in the tissues and to verify if and to what extent alterations of mechanical and biochemical cardiac properties induced by ischemia in the myocardium may be thus prevented. Ten rats had sodium selenite (6 micrograms/day) added to their drinking water for 4 weeks, while 10 control rats received no treatment. At the end of 4 weeks, the hearts were perfused by the Langendorff technique with oxygenated Krebs-Henseleit solution at a rate of 10 ml/min for 30 minutes at 37 degrees C.

Efferent limb of the coronary vasoconstrictor reflex elicited by distension of the descending colon in anesthetized dogs.

Distension of the descending colon elicits reflex coronary vasoconstriction. To study the efferent branch of this reflex, experiments were performed on 5 dogs anesthetized with pentobarbitone. A pouch was formed from the distal 15 cm of the descending colon and distended at constant pressure (54 +/- 8.

Haemodynamic effects of distension of the descending colon in anaesthetized dogs.

1. This study was undertaken to determine whether distension of the descending colon in anaesthetized dogs reflexly affects the heart rate, arterial blood pressure or the left ventricular inotropic state. 2.

The efferent mechanisms of reflex hemodynamic responses to distension of the descending colon in anesthetized dogs.

We have recently shown that distension of the descending colon in anesthetized dogs causes reflex increases in heart rate, aortic blood pressure and the maximal rate of rise of left ventricular pressure, involving afferent pathways in the hypogastric nerves. In this study we have examined the efferent mechanisms involved in those responses. The descending colon was distended using Ringer solution at constant pressure in 13 anesthetized dogs.

Reflex effects of descending colon distension on coronary blood flow in anesthetized dogs.

To find out whether distension of the descending colon reflexly affects coronary blood flow, experiments were performed in nine dogs anesthetized with pentobarbitone. The descending colon was isolated between ligatures and distended with warm Ringer solution at a steady intraluminal pressure. Arterial blood pressure was prevented from changing by withdrawing blood from the left femoral artery.

The effect of distension of the urinary bladder on left ventricular inotropic state in anesthetized dogs.

To decide whether distension of the urinary bladder reflexly affects the left ventricular inotropic state, experiments were performed in eight dogs anesthetized with pentobarbitone. After cannulation of both ureters the urinary bladder was repeatedly distended through a urethral catheter with warm Ringer solution at a steady intravesical pressure. The maximal rate of rise of left ventricular pressure (dP/dtmax) obtained at constant heart rate and cardiovascular pressures was used to assess changes in left ventricular inotropic state.

The heart as a biological clock: phase-locking between heart and efferent vagal activity.

Experiments were performed to evaluate whether the negative inotropic effect of efferent vagal stimulation is more strictly related to the number of stimuli falling with each cardiac cycle (St/c) or to the number of stimuli per second (St/s). Therefore, vagal stimulations were performed in anaesthetized dogs either with constant frequency (CONT), or with trains of 3 stimuli triggered by each atrial activation (SYNCHR). An atrial contractility index was measured while increasing heart rate by artificial heart pacing during CONT and SYNCHR vagal stimulations.

Small changes in heart rate following alpha-1 adrenoceptor stimulation in the anaesthetized dog.

In a previous work (1) we observed a weak alpha-1 adrenoceptor mediated chronotropic effect in anaesthetized dogs: the intracoronary injection of 100 micrograms of amidephrine, an alpha-1 agonist, increased heart rate by 2.5 +/- 0.8 bpm (mean +/- SEM).

Cervical efferent vagal stimulation related or unrelated to cardiac cycles: comparison of negative atrial inotropic effects.

Efferent cervical vagal stimulations were performed in 4 anesthetized dogs, either with trains of stimuli of constant frequency (CONT), or with brief trains, triggered by the atrial electrical activity (TRIG). Heart rate was increased by cardiac pacing during vagal stimulations. Negative inotropic effects of vagal stimulations, evaluated as changes in atrial contractility, were partially inhibited by cardiac acceleration during CONT, but were unaffected during TRIG.

Heart rate variability at the onset of efferent vagal stimulations in the rabbit.

Vagal stimulations were performed in 6 anesthetized rabbits for single cardiac cycles. The distribution of effects over 6 consecutive cardiac cycles was described as a function of varying intervals between P waves and stimuli (P-St): the response on the first couple of cycles is affected by P-St whilst the effects decline regularly over successive cycles. Stimulation of 6 consecutive cycles showed rapid rise and subsequent slow increment of the response.

Effects of combined stimulation of right and left vagus nerves on heart rate in rabbits.

The negative chronotropic effects of combined stimulations of the right and left vagus nerves were compared with the effects of single nerve stimulations in 10 urethan anesthetized rabbits. The combined stimulations gave smaller effects than single nerve stimulations at double frequency, over a wide range of frequencies: this was more evident for the right vagus compared with right plus left, rather than vice versa. It is concluded that the effects of combined stimulations are partially occluded and that the left vagus has smaller effects than the right vagus, although such difference becomes apparent only with combined stimulations.

Effect of peptichemio and of peptichemio plus hydrocortisone on growth and alkaline phosphatase activity in HeLa cells in vitro.

The actions of Hydrocortisone, Peptichemio and of Peptichmio + Hydrocortisone mixture in HeLa cells have been experimented. The results show an increase of cell number in the controls and a lower, but not statistically different growth, in the Hydrocortisone-treated cultures. In the cultures treated with peptichemio the growth is hardly evident, in the ones treated with the Hydrocortisone + Peptichemio mixture, the cell number is decreasing with time.

Biochemical and cytochemical effects of cytosine arabinoside (ARA C) and hydrocortisone on HeLa cells.

The biochemical and cytochemical effects of cytosine arabinoside (Ara C) and of hydrocortisone on HeLa cell in vitro have been studied. In cultures treated with Ara C, a relationship exists between the cytocidal effects of the drug and an increase in alkaline phosphatase. Although hydrocortisone had no influence on the proliferative rhythm, it induced an increase in alkaline phosphatase.