Cardiac alterations are thoroughly studied in experimental myocardial infarction. However, few data are known about myocardial microcirculation (MM) because of difficulties in its revelation. Objective: Aim of the present research is focused on assessment of morphofunctional alterations of MM in noncoronarogenic myocardial injury in 1h and 24h after adrenaline (Adr) injection. Methods: Experiments were conducted in albino male rats that were divided into control animals (n=8), and 2 experimental groups (n=6 each) that were exposed to cardiotoxic dose of 0.18% Adrenaline hydrotartrate (0.5 ml/kg, i.v.) under anesthesy and decapitated in 1h and 24h, respectively. MM was studied on left ventricle sections by modified Gomoris method. Mean capillary diametre (D) and diffusion space (DS) were measured by ocular micrometer. Capillary density (CD) per mm3 of myocardial tissue was assessed as total length (L) of capillaries. Capillary metabolic surface (CMS) was calculated as πDL, and capillary bed capacity (CBC) as πR2L (R – capillary radius). Statistical analysis was conducted by Students t-test. Data present as mean ± STD. Results: Data obtained showed that capillaries in control myocardium located parallel, capillary walls were homogeneously stained, striation of cardiomyocytes (CM) could be observed. An hour following injection the capillary perfusion was disrupted, striated structure of CM was not visualised locally. Moreover, increase of DS, insignificant dilation of capillaries, decrease of total L with subsequent reduction of CMS and CBC occurred. In 24h after Adr injection D decreased along with DS reduction and increase of CD. Meanwhile, the CMS and CBC did not restore.
* - p<0.05, ** - p<0.01-significance of differences vs control, ^-p<0.05 between experimental groups | Groups | D (mkm) | L (mm) | CMS (mm2) | CBC (mm3) | DS (mkm) | | Control | 6.48±0.2 | 2035±85 | 42.64±1.1 | 0.065 ±0.004 | 13.3±0.7 | | Adr 1h | 6.83±0.1 | 1701±71** | 36.47 ±1.3* | 0.069 ±0.002* | 14.34 ±0.3* | | Adr 24h | 5.79±0.2* | 2169±60^ | 39.43±1.6 | 0.054 ±0.027**^ | 12.86±0.5 |
Conclusion: Results obtained allow concluding that early stage (1h) noncoronarogenic alterations of MM express in decrease of local myocardial blood supply which may lead to myocardial necrosis, whereas Adr-induced MM changes tend to diminish in 24h.
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J. Vasc. Biol. 42, Sup:2 (2005) p92