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Biomedical subjects

H Lagercrantz

Publications and source records attributed to H Lagercrantz.

At least 217 records · Page 12Linked to original sources
PubMed1977

Catecholamine release in the newborn infant at birth.

Catecholamines were determined by a fluorimetric technique in umbilical blood which was collected from newborn infants immediately after birth. The mean catecholamine concentration was 62.1 nmol/liter in the umbilical artery and 29.3 nmol/liter in the umbilical vein of newborn full term infants delivered uneventfully. This value is considerably higher than in resting adults. Similar levels of catecholamines were seen after elective cesarean sections, whereas considerably higher levels were found after breech deliveries. In the full term asphyxiated infants about a 4-fold increase of the catecholamine concentration was found in both the umbilical arterial and venous blood. The amine concentration level correlated inversely to the pH below 7.25 (10 log catecholamine concentration versus pH, r = -0.71). Preterm infants had, in general, lower amine levels than full term infants both after uneventful deliveries and after intrauterine asphyxia. The catecholamine levels were considerably increased in the newborn infants who showed some kind of abnormal fetal heart rate variation during the last hour before birth; in particular baseline changes were associated with high levels whereas only a moderate increase was seen after loss of beat-to-beat variation.

Apgar Score↗
PubMed1976

Ultrastructrual effects of chemical sympathectomy on brown adipose tissue.

Adult rats maintained at 20-22 degrees C, were exposed to 4 degrees C for 30-60 min and injected with 50 or 100 mg/kg 6-hydroxydopamine (6-OHDA) in an attempt to achieve a similar degree of chemical sympathectomy of nerves terminating among the adipocytes and the smooth muscle cells of the blood vessels in the interscapular brown adipose tissue (BAT). After 1, 4 or 10 days the pads of BAT were removed and small sections from each pad prepared for electron microscopy; the remaining tissue was used for noradrenaline (NA) analysis for fluorescence histochemistry. Ultrastructural observations showed that 24 h after the 6-OHDA injection virtually all noradrenergic nerve terminals were distorted and contained aggregates of degenerated cell organelles. The destruction could be correlated with a disappearance of fluorescent varicosities and a reduction of measurable NA to 8-12% of the control value. There was no differential toxic effect of 6-OHDA on the terminals among the adipocytes compared to those associated with blood vessels. Thus, treatment with 6-OHDA is more effective than previous attempts using immunological or surgical methods to produce sympathectomy, because both of the latter methods only eliminate the innervation of the blood vessels and spare the nerve terminals of the adipocytes. 4 days after 6-OHDA injection there was no improvement in the morphology of the terminals but after 10 days there was an increase in the number of terminals and axons with a normal appearance and this was paralleled by an increase in extractable NA to 50% of the control value. Because of the relatively rapid recovery of NA content and reappearance of terminals of normal appearance within 10 days after 6-OHDA injection, these animals should be injected weekly when a more permanent sympathectomy of adipocytes and blood vessels is desired.

Adipose Tissue, Brown↗
PubMed1976

Gel electrophoresis of soluble and insoluble proteins of noradrenergic vesicles from ox splenic nerve: a comparison with proteins of adrenal chromaffin granules.

Polyacrylamide gel electrophoresis of a soluble extract of purified large dense-cored vesicles (noradrenergic vesicles) from ox splenic nerve revealed 13 proteins, 7 of which had mobilities close to those of seven of the soluble proteins in adrenal chromaffin granules. Two of these proteins had the same mobilities as dopamine beta-hydroxylase and chromogranin A, respectively. The relative staining intensities of the latter two proteins were different: in noradrenergic vesicles, there was more dopamine beta-hydroxylase than chromogranin A; whereas in chromaffin granules, chromogranin A was the major protein. Gel electrophoresis of the water-insoluble proteins of noradrenergic vesicles, dissolved in sodium dodecylsulphate, revealed 5 proteins, 5 of which had mobilities close to those of 5 proteins present in the membranes of chromaffin granules. Three of these proteins had mobilities similar to those of dopamine beta-hydroxylase, chromogranin A and chromomembrin B, respectively. One of the proteins was probably serum albumin, which was also present as a contaminant in the soluble extract of noradrenergic vesicles. These findings are consistent with earlier studies in which dopamine beta-hydroxylase, chromogranin A and chromomembrin B have been identified as constituents of noradrenergic vesicles by enzymatic or immunochemical assay methods. They also indicate further qualitative similarities between the noradrenergic vesicle and the chromaffin granule, in that a total of 7 soluble and 5 insoluble proteins might be common to both particles. However, gel electrophoresis also confirms that quantitative differences exist between the relative proportions of the soluble proteins and shows that dopamine beta-hydroxylase is the major soluble protein of the noradrenergic vesicles isolated from splenic nerve trunks.

Adrenal Medulla↗
PubMed1976

Chemical sympathectomy of interscapular brown adipose tissue.

Adult non-cold adapted rats were injected with 6-hydroxydopamine (6-OHDA) or saline and their interscapular brown adipose tissue (BAT) was removed after appropriate periods of time. Fluorescence histochemistry of control BAT demonstrated the presence of an extensive network of varicose fibers among the adipocytes and at the blood vessels. This was confirmed by electron microscopy which also revealed large and small dense core vesicles sparsely distributed in axons and terminals indicating the presence of noradrenaline (NA). After 6-OHDA injection the fluorescence from varicosities was abolished both among the adipocytes and at the vessels. Thus, chemical sympathectomy was more effective than surgical- or immunosympathectomy, which spare the innervation of adipocytes. Parallelling the disappearance of fluorescence was a significant decrease of measurable NA. During recovery the extractable NA increased before the reappearance of fluorescent varicosities. This could be explained by transmitter accumulation in the nervetrunks within the tissue, which, in general, appeared unaffected by 6-OHDA. A large number of cells with a strong yellowish fluorescence distributed through the BAT was unaffected by 6-OHDA. There was no evidence for the presence of intrinsic ganglia.

Adipose Tissue, Brown↗
PubMed1975

On the soluble phase of adrenergic nerve vesicles: correlation of matrix density and biochemical composition.

Highly purified sympathetic nerve vesicles isolated from bovine splenic nerves were treated by hypo-osmotic shocks, freeze-thawing or incubation in the absence or presence of ATP and MgCl. The vesicle preparations were then studied morphologically by electron microscopy and their content of noradrenaline (NA), and soluble proteins analyzed biochemically with special regard to dopamine beta-hydroxylase (DBH). Hypo-osmotic shocks released about 25 per cent of the NA and protein content and about 8 per cent of the DBH activity. This treatment induced swelling of the vesicles but their membranes remained unruptured and they still contained dense cores. Freeze-thawing released about 35 per cent of the NA, 25 per cent of the proteins and 11 per cent of the DBH. After the latter treatment some matrix material still remained in most vesicles but many were less stainable than the intact vesicles in cold control preparations. During incubation at 30 degrees C in an isotonic sucrose-phosphate medium for 30 min the vesicles released most of their NA and soluble DBH activity as well as much of their matrix density. After incubation at 37 degrees C for 30 min most vesicles appeared translucent. After incubation at 30 degrees C for 30 min in the presence of ATP and MgCl the vesicles lost most of their original NA content but retained their DBH activity and most of their matrix density. The results indicate that there is not always a correlation between NA content and retention of matrix density which suggests that DBH might be a component of a macro-molecular complex responsible for the staining reaction taking place in the maxtrix of NA depleted vesicles. This hypothesis is further supported by the finding of striking similarities between DBH isolated from chromaffin granules and the granular and fibrillar material surrounding the nerve vesicles after depletion.

Adenosine Triphosphate↗
PubMed1975

Potentiation by prostaglandins e1, e2, and f2alpha of the contraction response to transmural stimulation in the bovine iris sphincter muscle.

The contraction response to transmural stimulation in the bovine iris sphincter muscle was abolished by atropine but was left virtually unchanged by hexamethonium, and by adrenergic neuron and receptor blockers, indicating activation of postganglionic cholinergic nerve fibres. Low doses of prostaglandins e1, e2 and F2alpha (0.1-5.3 ng/ml) consistently and apparently in a dose-dependent manner enhanced the contraction response to transmural stimulation. Prostaglandins E1 and E2 were equipotent while F2alpha was at least 10 times less active. Within the same dose range the prostaglandins also enhanced the contraction response to exogenous acetylcholine, indicating that part of the enhancing effect of the prostaglandins on neuromuscular transmission was due to a postjunctional action. A spontaneous increase in tone of the preparation commonly occurred about 1 h after the beginning of the experiment. SC 19220, a potent antagonist of prostaglandin action, reduced the tone and the contraction responses as well as the enhancing effect of the prostaglandins. It is concluded that prostaglandins might serve the function of controlling neuroeffector transmission and muscular tone in the sphincter muscle of the bovine iris.

Acetylcholine↗