Heterogeneous control of blood flow amongst different vascular beds

Abstract

The control and maintenance of vascular tone is due to a balance between vasoconstrictor and vasodilator pathways. Vasomotor responses to neural, metabolic and physical factors vary between vessels in different vascular beds, as well as along the same bed, particularly as vessels become smaller. These differences result from variation in the composition of neurotransmitters released by perivascular nerves, variation in the array and activation of receptor subtypes expressed in different vascular beds and variation in the signal transduction pathways activated in either the vascular smooth muscle or endothelial cells. As the study of vasomotor responses often requires pre‐existing tone, some of the reported heterogeneity in the relative contributions of different vasodilator mechanisms may be compounded by different experimental conditions. Biochemical variations, such as the expression of ion channels, connexin subtypes and other important components of second messenger cascades, have been documented in the smooth muscle and endothelial cells in different parts of the body. Anatomical variations, in the presence and prevalence of gap junctions between smooth muscle cells, between endothelial cells and at myoendothelial gap junctions, between the two cell layers, have also been described. These factors will contribute further to the heterogeneity in local and conducted responses. © 2000 John Wiley & Sons, Inc. Med Res Rev, 21, No. 1, 1–60, 2001

Shear stress-induced upregulation of connexin�43 expression in endothelial cells on upstream surfaces of rat cardiac valves

“…There are considerable discrepancies in reports concerning distribution of endothelial connexins, especially Cx43, in the vasculature (see Hill et al 2001 for review). For example, Yeh and coauthors (1997) found that endothelial cells in rat aorta highly express Cx43 while Bruzzone and coauthors (1993) reported that Cx43 was not highly expressed in aortic endothelium.…”

Expression of homocellular and heterocellular gap junctions in hamster arterioles and feed arteries

“…The respective hexamers dock in the extracellular space to form an intercellular trans-membrane channel [9]. Of the more than 20 mammalian Cxs characterized to date, Cxs37, 40, 43 and 45 have been described in vascular tissue [10]. However, significant heterogeneity occurs in the expression of these four Cx subtypes amongst different arteries (see Ref.…”

“…However, significant heterogeneity occurs in the expression of these four Cx subtypes amongst different arteries (see Ref. [10]). In the endothelium, Cxs 37, 40 and 43 have been described in a number of different vessels [11] (see Table 2 in Ref.…”

“…In the endothelium, Cxs 37, 40 and 43 have been described in a number of different vessels [11] (see Table 2 in Ref. [10]). Expression in the media, however, is more controversial.…”

Anaesthetic Effects on the Hepatic Portal Vein and on the Vascular Resistance of the Tail of the Chinook Salmon (Oncorhynchus tshawytscha)

“…Thus blood vessels of the tail make a substantial contribution to total systemic vascular resistance and the maintenance of central blood pressures. Vascular tone in vertebrates is a compromise between vasoconstrictor and vasodilator pathways and the state of the vascular smooth muscle contraction constitutes the major determinant of resistance (Baum 1977;Satchell 1991;Hill et al 2001). In fish as in mammals, arteries and arterioles are presumed to be the major source of resistance (Olson 1998) and sympathetic nerves innervate systemic blood vessels of most teleost fishes (Morris and Nilsson 1994).…”