Humoral Factors Involved in the Induction of Liver Regeneration in the Rat.

Abstract

In previous work lthe relationships between liver regeneration in rats, age and carcinogenesis with azodyes were investigated ( 1,2). This is a report on further investigations with the emphasis on the medhanism contrnlling liver regeneration.In vitro experiments. In order to investigate the possibility of the existence of humoral factors involved in liver regeneration, blood sera from partially hepatectomized andcontrol rats were compared with respect to their action: a ) on the initial growth response of primary rat liver explants cultivated in vitro, and b) on the growth period of in vitro cultures of a strain of normal rat fibroblasts. In the first series 24 male rats, 6 to 10 months of age grouped in pairs, were used. The experimental procedure emplbyed on each pair was as follows: -4 partial hepatectomy consisting of the removal of the two main lobes of the liver was performed on one of the partners and a sham operation consisting of a laparotomy and manipulation of the liver on the other. Since hepatectomy reduces food uptake, the diet of the control was reduced in order that his food uptake would not exceed that of the hepatectomized rat. Twenty-four hours after the operation 6he animals were bled and the sera o'btained were tested within 48 hours. Liver from a male rat 3 weeks of age was used as test tissue. A small piece of the tissue was cut up in the fluids to be used as culture medium and explanted directly on the glass wall of roller tubes without the use of plasma or embryo extract. Six tubes containing 6 fragments each were set up for each

Serum Proteins of Rats after Partial Hepatectomy.

“…The assumption that the remarkable increase in mitotic activity associated with some stages of restoration of liver tissue after partial hepatectomy of rats is mediated by humoral factors has been supported by findings obtained after injection of serum from hepatectoinized animals (1)(2)(3) and by results of parabiosis experiments (4)(5)(6). Changes in plasma and serum proteins of rats after partial hepatectomy have been investigated (7-1 1 ) .…”

“…Small doses of nicotine injected into the thoracic aorta stimulate the adrenal medulla resulting in marked increases in levels of circulating catechol amines along with corresponding increases in heart contractile force (1,2). Our experiments were designed to study effects of previous reserpine treatment on (a) responsiveness of the adrenal medulla to chemical stimulation and (b) reactivity of the cardiovascular system to endogenously released catechol amines.…”

<i>In vitro </i>Evidence for a Renotrophic Factor in Renal Compensatory Hypertrophy

“…The control of compensatory liver hyperplasia by a humoral factor is well established [3,19]. The specificity of this primary renal tissue culture was in vestigated by incubating plasma from partially hepatectomized hamsters with tissue cultures in comparison with similarly treated cultures incubated with sham and uninephrectomized plasma.…”

Effects of post‐hepatectomized rat sera on cultured cells

“…Sigel et al (1967), using liver autografts, concluded that a humoral factor probably regulated hepatic regeneration. Glinos and Gey (1952) concluded from their experiments that the factor was not stimulatory but, rather, inhibitory in nature. The same conclusions were reached by Moya (1963) and Fisher et al (1963).…”