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Biomedical subjects

S Dolezel

Publications and source records attributed to S Dolezel.

At least 37 records · Page 2Linked to original sources
PubMed1984

Mechanisms causing the death of 8 calves surviving with implanted artificial heart from 31 to 173 days.

Causes of the death of four animals from the total of eight were technical failures (diaphragm perforations, disconnection of the quick-connector, and a failure of the supply of electric current which could not be prevented). Causes of the death of the remaining four animals were embolisation in the brain stem, embolisation in the superior mesenteric artery leading to diffuse peritonitis, ruptures of aorta and hemocoagulation disorder causing fatal gastrointestinal bleeding.

Animals↗
PubMed1984

Cardiac adrenergic innervation after instrumentation of the coronary artery in dog.

A fine methacrylate ring (not constricting the artery) was placed around the ramus interventricularis anterior (RIA) of the left coronary artery in dogs. By means of Falck's histochemical technique an extensive degeneration of the vasomotor and cardiomotor adrenergic innervation of ventricles was detected 14 days after the procedure. The innervation of atria remained intact. The surgical intervention as well as the scarring process (which compressed the conducting parts of axons composing the perivascular nerves) induced the degeneration. The results have important implications for experiments with instrumented arteries.

Animals↗
PubMed1984

[Relative volume of open capillaries in the skeletal muscles of rats with chronic local arterial hypotension].

A modification of Pickworth's method for detection of open capillaries was used. The modification is based on freezing an organ in situ with liquid propane, cooled with liquid nitrogen, followed by lyophilization of the preparation and its fixation in gaseous formaldehyde. It was shown in rat experiments that the number of functioning capillaries in m. gastrocnemius and m. soleus 14 and 90-12 days after reduction of pressure in the hindquarter of the body with the narrowing of the abdominal aorta lumen was practically the same as that in the control animals. The data support the view that reduction of the hydraulic resistance in the area of regional hypotension does not correlate with increase in the number of parallel-functioning vessels.

Animals↗
PubMed1984

[Effect of long-term arterial hypotension on the relative volume of functioning capillaries in working skeletal muscles].

In control rats, the relative red cell volume, mirroring the number of the functioning capillaries, was substantially greater in the soleus than in the gastrocnemius muscle, while the rise of this parameter seen during contraction of both the muscles, provoked by stimulation of the sciatic nerve, amounted to 37 and 54%, respectively. Fourteen days and 3-4 months after abdominal aorta constriction by a metal spiral, that produced a 30-50% lowering of the blood pressure in the vessels of the animal's body posterior, contractions of the gastrocnemius muscle did not provoke any increase in the relative red cell volume, whereas contractions of the soleus muscle were accompanied by a marked elevation of the relative red cell volume. It is assumed that the mechanisms underlying the working hyperemia of the gastrocnemius and soleus muscles are different.

Animals↗
PubMed1980

Elastic tissue and smooth muscle volume in elastic and muscular type arteries in the dog.

1. Relative elastic tissue and smooth muscle volumes were determined by a stereological point-counting method in arteries with a progressively diminishing diameter, from the aorta towards the periphery. 2. The volume relationship between the smooth muscle cell and its nucleus was determined by the same method. Mean nuclear volume amounted to 6.9% of total smooth muscle cell volume. 3. Relative elastic tissue volume fell from the aorta towards the peripheral arteries, from 22.6% in the ascending aorta to 4--6% in the smallest arteries examined. 4. Relative smooth muscle volume was practically the same and differences between the individual values in the vast majority of arteries examined were non-significant. Total smooth muscle volume, calculated from the volume of the smooth muscle cell nuclei, varied mostly from 45 to 55%. 5. It can be concluded from these results that the ability of small and medium muscular type arteries to change their diameter actively by muscular contraction (as against elastic type arteries, in which this ability is less expressed) is facilitated not only by the organization of the structural components of the arterial wall, but also by the lower elastic tissue volume, which is compensated by the volume of the other passive components of the vascular wall, while relative smooth muscle volume remains the same.

Animals↗
PubMed1980

Monoaminergic pathways to the coronary arteries and to the myocardium.

The monoaminergic innervation of the coronary vessels and of the myocardium in dogs was examined by means of degenerative techniques: (i) local perivascular neurotomy was performed at the origin of the left coronary artery; (ii) the stellate ganglion was removed bilaterally. Evaluation of the neural degeneration pattern led the suggestion that three types of neurons at least exist within the heart: (i) neurons innervating the coronary vessels both in the ventricles and in the atria; (ii) neurons innervating the ventricular myocardium, and (iii) neurons innervating the atrial myocardium. The post-ganglionic fibres of the stellate ganglion innervate the vessels of the whole heart. Their contribution to the innervation of the ventricular myocardium represents about 30%.

Animals↗
PubMed1979

Role of the vagus in control of the major conduit coronary artery in the dog.

Using El Badawi and Schenk's modification of Karnovski's method for the demonstration of acetylcholinesterase, the authors found cholinergic fibres both in the perivascular connective tissue and directly in the wall (in the adventitia) of the major coronary arteries; the fibres were distributed regularly around the circumference of the arteries. In the case of the smaller intramyocardial arteries, the cholinergic fibres were concentrated at two poles of the blood vessel; none were present in the wall of the veins. The shape and topography of the coronary cholinergic arterial plexus resemble the shape and topography of the coronary sympathetic adrenergic system. In apparent contradiction of this finding, stimulation of the cervical vagus did not affect the diameter of the large coronary arteries. Since acetylcholine (6--10 micrograms/kg i.v.) produced a mean 7.4% increase in the diameter of the ramus interventricularis ventralis, we concluded that there are no postgangliar cholinergic fibres of vasomotor significance for the large coronary arteries in the cervical vagus. The specific acetylcholinesterase activity found in the wall of these vessels belongs either to cholinergic terminals whose ganglion cells are not located in the vagal ganglion, or to cholinergic axones terminating outside the wall of the large coronary arteries.

Acetylcholinesterase↗