GLORIA — GEOMAR Library Ocean Research Information Access

Hits per page

hits 1 - 2 | 2 hits

Sorting

Electronic Resource

THE INFLUENCE OF ALTERATIONS IN THE CARDIAC LOADING CONDITIONS ON INDICES OF MYOCARDIAL CONTRACTILITY IN THE ANAESTHETIZED DOG (1977)

Angus, J. A. ; Richmond, D. R. ; Cobbin, L. B. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Clinical and experimental pharmacology and physiology 4 (1977), S. 0

add to mindlist on the mindlist

Details

ISSN: 1440-1681

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Medicine

Notes: 1. An online analogue computer was used to measure myocardial contractility as the ratio dP/dt/IIT where dP/dt is maximum rate of change of left ventricular pressure and IIT is integrated isometric tension.2. In the open thorax anaesthetized dog, max (dP/dt) and dP/dt/IIT were compared during alterations in preload, by partial vena caval occlusion, and changes in after-load obtained by acetylcholine injections and by partial occlusion of the descending thoracic aorta.3. A fall in preload lowered max (dP/dt) but did not alter dP/dt/IIT A rise and fall in afterload produced respectively an increase and decrease in max (dP/dt) but dp/dt/IIT was unaltered.4. From expanded time base recordings, the time from the start of aortic flow (EM flowmeter) to max (dP/dt) was measured to indicate the relationship between valve opening and rnax (dP/dt). At low preload or elevated afterload the aortic valve opened well after max (dP/dt) had been reached. When the afterload fell, max (dP/dt) occurred after the opening of the aortic valve.5. Positive inotropic stimulation following intravenous isoprenaline caused a marked elevation in dP/dt/IIT. However, the rise in max (dP/dt) was attenuated in comparison to dP/dt/IIT by a marked fall in afterload and thus early opening of the aortic valve.6. It is concluded that max (dP/dt) is very sensitive to alterations in preload or afterload but the index——-dP/dt/IIT is normalized so that changes in end diastolic fibre length do not alter this index. When the afterload falls max (dP/dt) is no longer determined in the isovolumic phase of contraction so that magnitude of rnax (dP/dt) is reduced. However, it is an empirical finding that IIT also falls so that the ratio is unaltered. dP/dt/IIT is a useful index of myocardial contractility that is insensitive to changes in preload or afterload.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1440-1681.1977.tb02611.x

Permalink

	Location	Call Number	Limitation	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Effect of collagen crosslinking on the rate of resorption of implanted collagen tubing in rabbits (1977)

Chvapil, M. ; Owen, J. A. ; Clark, D. S. ; [et al.]

Hoboken, NJ : Wiley-Blackwell

Journal of Biomedical Materials Research 11 (1977), S. 297-314

add to mindlist on the mindlist

Details

ISSN: 0021-9304

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Medicine , Technology

Notes: Collagen tubes were tanned with glutaraldehyde for different periods of time. Some were oxidized with periodate and sterilized with either 60Co (1.5 Mrad) or propylene oxide. The tubes were coated with polyfilamentous polyester fabric, filled with x-ray contrast material, and implanted subcutaneously in rats and rabbits. Rate of resorption was ascertained by x-ray procedure of progressive leakage of contrast material.A close relation between tanning time of the collagen fabric-combined prostheses and rate of their resorption in subcutis was found in both rats and rabbits. In rabbits, however, the implants were resorbed at a significantly faster rate than in rats. No effect of oxidation of collagen on the resorption was observed. Collagen tubes tanned for shorter time periods and sterilized with propylene oxide were more resistant to degradation than those sterilized with irradiation. This difference was absent, however, with material tanned for longer times.The mechanism of resorption of implanted collagen tubes was studied by morphological methods. The role of inflammatory cells in resorption is documented. The paper indicates the advantages as well as limits of the x-ray method of studying the resorption rate of biodegradable materials.

Additional Material: 10 Ill.