Search PubMed⌕ Search

Biomedical subjects

B Folkow

Publications and source records attributed to B Folkow.

At least 145 records · Page 8Linked to original sources
PubMed1975

Central neurohormonal mechanisms in spontaneously hypertensive rats compared with human essential hypertension.

Consideration of the results obtained in studies of spontaneously hypertensive rats indicates that these animals can serve as useful models for perhaps the most common type of essential hypertension of man. Other variants of essential hypertension probably occur where the relative balance between the genetic elements predisposing to high blood pressure may be somewhat different.

Animals↗
PubMed1975

Arterial pressure, cardiac output and systemic resistance before and after pithing in normotensive and spontaneously hypertensive rats.

After complete cardiovascular denervation mean arterial pressure (MAP) falls to almost equally low levels in spontaneously hypertensive rats (SHR) and normotensive control rats (NCR). This has earlier been suggested to indicate a dominance of neurogenic mechanisms in established SHR hypertension. -- In the present study, total peripheral resistance (TPR) remains, however, some 35 per cent higher in adult SHR than in NCR after pithing while cardiac output (CO), and stroke volume, is 35 per cent lower in SHR. These opposite differences in TPR and CO after denervation, resulting in equal MAP levels in SHR and NCR, seem rather to be a consequence of the rapidly established structural adaptation that affects all SHR high-pressure cardiovascular sections. Thus, the SHR precapillary resistance vessels display thickened walls and luminal narrowing, which keeps TPR higher than in NCR even during maximal vasodilatation. Due to hypertrophy, the SHR left ventricle exhibits a reduced myocardial stretch for a given filling pressure and stroke volume is consequently reduced more than in NCR after complete denervation. -- Paradoxically, therefore, rather than reflecting any dominance of neurogenic mechanisms in established SHR hypertension the MAP equalization in SHR and NCR after cardiovascular denervation emphasizes the hemodynamic importance of cardiovascular structural changes present in hypertension.

Animals↗
PubMed1975

The influence of rheological and collapse factors on pre- and post-capillary flow resistances in the skeletal muscle vascular bed of the cat.

The importance of passive-elastic changes of vascular dimensions and shifts in regional effective viscosity for the pre-/postcapillary resistance ratio (RA/RV), and hence mean capillary pressure (PC), was analyzed in cat calf muscles. Reductions of mean venous distending pressure below 6-8 mm Hg induced marked RV increases due to escalating venous collapse. This mechanism tends to delimit the PC reductions and rate of transcapillary fluid absorption during intense precapillary vasoconstriction. Comparisons of RA/RV for erythrocyte suspensions (Hct 40-50) and cellfree perfusates at identical vascular dimensions showed that RA/RV was considerably higher, and PC correspondingly lower, for the erythrocyte suspension except at very low flows. This RA/RV difference increased with increasing flow and at very high flows PC was about 10 mm Hg lower during perfusion with the erythrocyte suspension. These findings apparently diverge from the known influence of the tube radius and linear flow velocity on effective in vitro viscosity of blood. Since distal precapillary and proximal capillary sections, both having smaller diameters than the erythrocytes, are located upstream to the point of filtration-absorption equilibrium, they contribute in this respect to RA. It is therefore suggested that the increasing RA/RV with erythrocyte perfusion, particularly at higher flows, is not due to genuine viscosity factors but to friction losses when cells in "bolus flow" are squeezed through the narrowest precapillary sections.

Animals↗