Effect of salt-induced hypertension on microvascular pressures in skeletal muscle of Dahl rats

Abstract

The purpose of this study was to determine the effect of salt-induced hypertension on the microvascular pressure profile in skeletal muscle. Measurements were made in the spinotrapezius muscle of anesthetized Dahl salt-sensitive (DS) rats fed either a high- (7%) or low-normal (0.45%)-NaCl diet for 4 wk. Age-matched Dahl salt-resistant (DR) rats on high- or low-normal salt diets were also studied. The high-salt diet had no effect on either arterial or microvascular pressures in DR rats. DS rats maintained on high salt developed arterial hypertension accompanied by a pressure increase of 49% in the feed arterioles and 31% in the transverse arterioles. Hypertensive DS rats exhibited a greater pressure drop across the small arteries, arcade arterioles, and distal arterioles, indicating that each of these segments contributes to increased whole organ resistance. Pressures in the collecting and draining venules were not elevated in DS on 7% NaCl, suggesting that increased precapillary resistance in salt-induced hypertension effectively shields the skeletal muscle capillary and venular networks from high hydrostatic pressures.

Nanoparticle inhalation alters systemic arteriolar vasoreactivity through sympathetic and cyclooxygenase-mediated pathways

“…One to three arcade bridge arterioles were studied per animal preparation. These arterioles are the site of the majority of vascular resistance in the spinotrapezius muscle and hence of major importance in regulation of blood flow in the muscle (Boegehold 1991). The arcade bridge arteriole originates from the thoracodorsal and 11th intercostal arteries at the proximal and distal ends, respectively, of the muscle forming a loop that contributes the entire blood supply for the arcading vascular network (Schmid-Schonbein et al 1991).…”

Structural adaptation increases predicted perfusion capacity after vessel obstruction in arteriolar arcade network of pig skeletal muscle

“…Similarly, the flow rate in each AO is given by Q AO,i ϭ (Pi Ϫ Pv)/RAO, where RAO is the downstream flow resistance associated with each AO. Flow rates in arteriolar vessels vary approximately in proportion to the cube of diameter (15), and AO resistance was therefore estimated as R AO ϭ (DAO/DTA) 3 ϫ RTA, where DAO is the corresponding AO diameter and DTA is the mean TA diameter. The flow rate in segment i was then given by Q i ϭ (Pj Ϫ Pk)/Ri, where Pj and Pk are the pressures of the end nodes of segment i, the flow resistance of segment i is Ri ϭ 128Li/(Di4), and Li and Di are its length and diameter.…”

Particulate Matter Exposure Impairs Systemic Microvascular Endothelium-Dependent Dilation

“…This preparation has been an essential tool in the fundamental understanding of capillary network development (Skalak and Schmid-Schonbein 1986); neurogenic, humoral, and myogenic control of microvascular resistance (Lash and Shoukas 1991; Nakamura and Prewitt 1991; Nurkiewicz and Boegehold 1998); and the physiologic roles of oxygen, nitric oxide, and calcium (Ca 2+ ) in microcirculation (Linderman and Boegehold 1999; Pries et al 1995; Toth et al 1998). Additionally, the spinotrapezius muscle preparation has been extensively used to characterize pathophysiologic microvascular consequences of chronic diseases such as diabetes (Kindig et al 1998), hypertension (Boegehold 1991; Nurkiewicz and Boegehold 1998; Zweifach et al 1981), and heart failure (Kindig et al 1999). Arterioles of the first branching order were studied because these vessels, together with their upstream feed arteries, are responsible for approximately 60% of total spinotrapezius muscle vascular resistance and therefore are of major importance for local blood flow regulation (Boegehold 1991).…”

“…Additionally, the spinotrapezius muscle preparation has been extensively used to characterize pathophysiologic microvascular consequences of chronic diseases such as diabetes (Kindig et al 1998), hypertension (Boegehold 1991; Nurkiewicz and Boegehold 1998; Zweifach et al 1981), and heart failure (Kindig et al 1999). Arterioles of the first branching order were studied because these vessels, together with their upstream feed arteries, are responsible for approximately 60% of total spinotrapezius muscle vascular resistance and therefore are of major importance for local blood flow regulation (Boegehold 1991). …”