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Biomedical subjects

C Pfeiffer

Publications and source records attributed to C Pfeiffer.

At least 73 records · Page 4Linked to original sources
PubMed1981

The carotid bodies of spontaneously hypertensive rats (SHR): a functional and morphologic study.

The parameters of the acid-base-state of the arterial blood were measured in spontaneously hypertensive rats of the Okamoto-strain (SHR) and in normotensive Wistar rats (NWR) of a random-bred strain. The animals were anaesthetized with chloralose-urethane and breathed normal air under sea-level conditions. Structure and size of their carotid bodies were studied by light-microscopic methods. When compared with the NWR, the SHR showed a respiratory alkalosis and enlarged carotid bodies. In the SHR, never in the NWR, the lumen of the branches of the glomic arteries was narrowed by pad-like structures. The data suggest that systemic hypertension leads to morphologically and functionally detectable alterations of both carotid body structure and function. The interdependence of arterial chemoreceptor activity, sodium household, and the adjustment of systemic arterial blood pressure is briefly discussed.

Animals↗
PubMed1981

The carotid bodies in spontaneously hypertensive (SHR) and normotensive rats--a study concerning size, location and blood supply.

Size, anatomical position and blood supply of the carotid bodies were studied by light microscopic methods in spontaneously hypertensive rats of the Okamoto-strain (SHR) and in normotensive Wistar rats (NWR) of a random-bred strain. In both groups of animals the single carotid body was usually supplied by only one glomic artery which most frequently derived from the external carotid artery, more rarely from the occipital artery and very seldom from the internal carotid artery. In general the carotid bodies were of ellipsoide shape and compact structure and as a rule closely located to the internal carotid artery. In the NWR at the origins of their glomic arteries almost regularly circular intraarterial cushions were found; in the SHR such cushions were only seen in a few cases, and if so than they were less clearly developed. In the SHR, never in the NWR, within the carotid body the lumen of some branches of the glomic arteries was narrowed by pad-like structures. When compared with the NWR the SHR showed enlarged carotid bodies and a respiratory alcalosis, suggesting that systemic hypertension leads to morphologically and functionally detectable alterations of both carotid body structure and function.

Animals↗
PubMed1979

[Anesthsiological experiences in experimental surgery].

The paper reports experience with methods of anaesthesia in rabbits, rats, mice, guinea-pigs, pigs, sheep, baboons, dogs and cats. Special problems of handling, mode of injection and intubation are discussed. A comprehensive survey of literature provides further information about the proposed patterns of anaesthesia and informs about other anaesthetic methods, not practised by the authors.

Alcuronium↗
PubMed1978

[Results of surgical treatment in intermittent divergent squint with deliberate overcorrection (author's transl)].

A review is given of 28 cases (39 surgical procedures) with intermittent exotropia. Prior to surgery a prismatic correction was prescribed and gradually increased to stabilize the objective angle. The amount of surgery was calculated to give a slight overcorrection (approximately 5 degrees). Follow up over a 6 months period revealed better results if overcorrection was achieved. Consecutive esotropia occured if the surgery did not make proper allowances for distance/near ratios of the objective angle. Secondary surgery was delayed up to 6 months. Spectacle occlusion followed by base-out prisms were prescribed in any case of overcorrection until bifoveal fixation could be maintained.

Adolescent↗
PubMed1978

[Ultrastructural and functional changes of rabbit myocardium after cholesterol feeding].

The myocardium was ultrastructurally investigated immediately after 12 weeks of feeding in one part of the animals and in the remaining animals 27--30 months after termination of the feeding period. At the same time, parameters of the myocardial contraction were measured immediately after the feeding at isolated trabeculae of the left ventricle and 27--30 months after the termination of the feeding at the left ventricle in situ. After the 12 weeks of feeding the morphometrically estimated intracellular lipid content rises from 0.23% (normal) to 5.26%. The mitochondria decline from 36.98% (normal) to 29.08%. The sarcoplasmic reticulum (SR) changes in a vesicular or vacuolar manner respectively. The contractility index Vmax of isolated trabeculae decreases insignificantly. The resting potentiation and the diastolic stiffness are increased. 27--30 months after termination of feeding the lipid content and the mitochondria are normal in comparison to controls of the same age. The vacuolar changes of SR and its cellular portion are increased. The contractility index of the heart in situ max (dp/dt)/P is decreased insignificantly. The velocity of relaxation is enhanced in comparison with controls. By comparing ultrastructural and functional findings it can be seen that variations in the contraction performance are accompanied by stronger changes of the cellular structure immediately after the feeding than 27--30 months after the termination of the feeding. At this time continuing small alterations in the contraction performance of the heart in situ are observed in addition to the reversibility of various characteristics of damage together with an increase in the Ca++-transporting SR and its alterations.

Animals↗
PubMed1978

[Changes in the excitation contraction coupling in the myocardium of rabbits fed a cholesterol-containing diet].

It was of interest whether a hypercholesterolemia after feeding a diet containing 2 g cholesterol in sunflower oil per day during 12 weeks induces changes of the myocardiac cells of rabbits which must not necessarily be the consequence of a diminished bloodstream on account of coronary stenosis or the consequence of a lesion of the wall of the vessels. The contractile force and the indirectly measured shortening velocity of the isometrically working papillary muscle out of the left ventricle were not reliably changed. As a result of the feeding the isometric force rose after paired pulse stimulation and after a pause during the rhythmic action, although a considerable deposition of fat within the cells and disseminated necrosis in the myocardium could be observed. Because of the increasing loss of sodium into sodium-free solution in parallel with an increasing sodium content of the myocardium it has been concluded that the permeability of the cell membrane for this ion should be elevated. Furthermore it is assumed that the activation of the ionic pumps is elevated which is recognizable from a higher positive inotropic action of both the application of strophanthine and the substitution of NaCl by LiCl. But it seems that one elevation could not completely compensate the other one. The mean value of the velocity of relaxation related to the isometric force was increased. It has been postulated that after the diet rich in cholesterol and sunflower oil the cardiac cell shows a retarded restitution of the contraction during the interval between beats and elevated content of calcium. This may be one of the causes for the observed necrosis besides the ischemic component of the injurant feeding.

Animals↗
PubMed1977

[Effect of free fatty acids on the heart: effects of nonanoic acid on contractility and postextrasystolic potentiation in the rat papillary muscle].

1. Nonanoic acid causes a depression in the contractile force of rat papillary muscles working isometrically. The effect depends on both the concentration of the fatty acid (0.1-1 mM) and the time of exposure (2-12 min), and shows a nearly complete reversibility. 2. Vmax-values derived from the force-velocity relation as well as the index of relation suggested by Meerson do not change in muscles exposed to nonanoic acid. During paired pulse stimulation with a 400 ms-delay of the second impulse, both the postextrasystolic potentiation and the time to reach a new steady level in the contraction amplitude are significantly increased. The speed of restituting the contraction after a twitch (resitution) is descreased. 4. The results suggest that the action site of nonanoic acid may be the excitation-contraction coupling system (including the action potential) rather than the contractile element or the relaxation of the muscle.

Action Potentials↗
PubMed1975

[Effect of D20 on contractility and excitation contraction coupling in the rat papillary muscle].

D2O decreases the isometric contraction force of papillary muscles from the left ventricle of rats. This effect can be compensated only partially by increasing the calcium content in the perfusion solution. Differences in the effect of D2O under different calcium concentrations point also to an action site other than at the contractile proteins. The enlargement of the restitution of contraction 300 msec after the basic beat, the diminution of the postextrasystolic tiation and the disappearance of postextrasystolic depressions because of high calcium potencontent in the bathing solution make it more probable that the action site lies in cell compartments which may be involved into the supply of activator calcium. The increasing occurrence of aftercontractions alredy at slightly enhanced extracellular calcium is in good agreement with this fact.

Animals↗