The heart, lung, kidney preparation

[Technical aspects of isolated organ perfusion devices]

An aspect of capital importance in the transplant field is the maintainance and preservation of organs during the ischemic phase. Organ susceptibility and injuries secondary to ischemia, organ procurement and transportation are still nowadays one of the main causes for organ failure. Effective artificial organ perfusion has remained a main goal for researchers in this field for more than 100 years. In the second half of the XXth century these techniques have been applied to experimental and clinical organ preservation, with the aim of extending the period of an effective storage (which guarantees an early and good function after the transplant). Primary goal of any organ preservation is to maintain integrity in every cell system in order to minimize those injuries which produces graft dysfunction.

Charles Arthur Lovatt Evans, 1884-1968

Charles Lovatt Evans, Emeritus Professor of Physiology, University of London, and a former Vice-President of the Royal Society, died on 29 August 1968, at the age of 84, at his home at Winterslow, near Salisbury. He was the foremost pupil and a lifelong associate of E. H. Starling, Jodrell Professor of Physiology at University College London, and eventually occupied the same chair. Lovatt Evans was born in Birmingham and spent the whole of his childhood and early manhood there. His father Charles Evans taught music— piano and violin—and was a man of many interests, of which ancient history was one, and he started to learn Greek when in his sixties. Although a humorist he had somewhat rigid views on religion, life and death, and held the view that the more you do for people the less they do for themselves, so Lovatt Evans was largely left to himself to decide upon his future and surmount the difficulties of finding ways and means. His mother seemed to him to be of rather an aloof nature, spending much of her time in intellectual pursuits often at the expense of her domestic duties. The result was that in his home life he was lonely.

Endothelium: a distributed organ of diverse capabilities

A historical survey of the growth of ideas about the circulation of the blood and about the endothelium is provided as a background to the specialized papers that follow. Over the years, in the course of clarifying its structure and function, the status of the endothelium has gradually evolved from that of an inert semipermeable barrier that determines the exchange of substances between blood vessels and tissue spaces to that of a specialized organ that is unusual in its dispersion throughout the body as the lining of blood vessels. This unique arrangement has enabled it to play different roles in different parts of the vascular tree and in different organs and to manifest distinctive responses to injury according to its structure and location. As a corollary, because its responsiveness is strongly influenced by its ambience and neighboring tissues, it seems inevitable that extrapolations from function in vitro to function in vivo require considerable prudence.

The basic requirements for the function of the isolated cell free perfused rat kidney

We have attempt to define experimental conditions which would overcome or minimize some of the well known functional limitations of isolated single pass kidney preparations. Rat kidneys were perfused with a Krebs-Henseleit solution containing the gelatine derivative Haemaccel as colloid. Perfusion was initiated in situ via the mesenteric artery. Arterial flow rate was measured continuously from the very onset of perfusion. Effective perfusion pressure was recorded distal to the perfusion capillary in the aorta. Aliquots of the venous effluate and of an arterial bypass solution were drawn through an O-2 electrode for the calculation of Q-o-2. First it was shown that the often observed initial vasoconstriction of the preparation which occurs immediately after cannulation of the kidney can be eliminated by rapid disconnection of the autonomic nerve supply. A more delayed gradual increase of renal resistance, which we observed after 30 min could be prevented by using sterile perfusion solutions. Using glucose as the only substrate fuel, fractional Na-reabsorption decreased to 65% 3 hrs after the onset of perfusion (T Na equals 27.3 muEq/g with min). When a substrate enriched sterile solution was used containing pyruvate, lactate, oxaloacetate, and glutamate, Na conservation of the isolated kidney could be maintained at a higher level. Fractional Na-reabsorption levelled off and was still 88% after 3 hrs (T Na equals 64.4 muEq/g with min). The results demonstrate that the transport function of the isolated kidney preparation critically depends on the supply with substrate hydrogen. Thus, the present system meets the basic requirements necessary for further micropuncture evaluation of renal function under the condition of isolated single pass perfusion.

A method of thymic perfusion and its evaluation

The development and evaluation of a method of isolated ex vivo perfusion of the rabbit thymus using diluted autologous blood is described.

The data indicate that the viability of the preparation is maintained at a satisfactory level during the period of perfusion.

These results suggest that the isolated perfused thymus would be a useful new approach to studies of thymus function.

Pulmonary and circulatory effects of fibrinopeptides

Bovine fibrinopeptide B and human fibrinopeptide A given in minute concentrations to rabbits, dogs, and lambs caused pulmonary hypertension, decreased effective pulmonary blood flow, decreased lung compliance, decreased ventilatory conductance, increased frequency and volume of ventilation, and increased differences in arterial and alveolar Pco 2 and Po 2 . These effects appeared immediately after injection of the peptides into the lesser circulation, increased for 15 to 30 min, and were detectable for as long as 70 min. Mean aortic pressure, heart rate, stroke volume, left and right atrial pressures, and cardiac output showed no systematic changes after injection of these peptides. On the contrary, bovine fibrinopeptide A given in equimolar doses elicited none of the pulmonary responses but induced increases in heart rate, stroke volume, and cardiac output without consistent changes in mean pulmonary or aortic pressure. These responses appeared within 3 min, increased for 5 to 10 min, and disappeared within an hour. Some possible relationships of fibrinopeptides to clinical syndromes characterized by respiratory distress, hypoxemia, pulmonary vasoconstriction, and diminished lung compliance are briefly discussed. It is speculated that the lung may be an active site of fibrinopeptide catabolism and that accelerated fibrinogen-fibrin conversion may cause pulmonary failure through fibrinopeptide-induced vasoconstriction and reduction in compliance.