Vascular anatomy and hydrostatic pressure profile in the hamster cheek pouch

Abstract

The purpose of this study was to describe the vascular architecture and blood supply to the hamster cheek pouch and to measure the intravascular pressure distribution in the entire pouch. Previous anatomic descriptions have focused either on the vasculature of the facial region or on the microcirculation of the cheek pouch tip. Micropressures in cheek pouch capillaries, terminal arterioles, and small venules have not previously been measured. Cheek pouches were prepared for examination under an intravital microscope using both everted and noneverted methods. Microvessel diameters were measured through a video system using a video micrometer, and intravascular hydrostatic pressures were measured with a servo null micropressure system. Blood vessels in the face and pouch were traced after injection of Microfil into the external maxillary artery. The results indicate that the pouch is supplied directly or indirectly by six small arteries in the neck and face. Fifty percent of the total pressure drop across the cheek pouch vasculature occurs in the small cheek pouch arteries, suggesting that these vessels are potentially important in controlling cheek pouch blood flow. The measurements of microvascular pressures and diameters in this study help clarify apparent discrepancies in similar measurements from previous studies.

Effects of vasoconstriction and vasodilatation on LV and segmental circulatory energetics

“…R circ is also equal to SVR Ϫ ¥R i , where ¥R i is the summation of the above identified resistances. These incremental resistances correspond very well (21) to measurements of pressure drop across the vascular elements in the hamster cheek pouch (5). From that comparison, we suggested that R A-Res involves arterial vessels as small as 60 m and that R V-Res also involves venous vessels as small as 60 m.…”

Arteriolar reactivity to pressure stimuli in hamsters with renal hypertension.

“…In addition, the arterioles of both the NT and hypertensive groups must exhibit good vascular tone, since maximal vasodilation with adenosine in the cheek pouch has been shown to nearly double wall tension in third and fourth order arterioles, with little change in tension of first and second order arterioles. 33 In the present experiment, the resting diameters of the larger arterioles was decreased in the RHT hamsters while the vasodilator tone was increased. Thus, the optimum point of stress may not have been altered in these arterioles; therefore, the altered reactivity of the third order arteriole may be due to a change in the sensitivity of the vascular smooth muscle to vasoactive stimuli.…”

Control and Coordination of Vasomotor Tone in the Microcirculation

“…Several distinct functional compartments can be distinguished in the vascular network: arteries, arterioles, capillaries, venules and veins. Conduit arteries (diameter, 1 to several millimeters) carry blood away from the heart through a divergent arborescence that reaches and penetrates into the tissues via the feed arteries (diameter, 100 to 500 µm) (Davis et al, 1986;Segal, 2000Segal, , 2005. These muscular vessels give rise to the arterioles (diameter, < l00 µm), which control and coordinate the blood flow distribution in such a way that each capillary is correctly supplied at the proper pressure (Mulvany, 1990;Segal, 2005).…”

“…These muscular vessels give rise to the arterioles (diameter, < l00 µm), which control and coordinate the blood flow distribution in such a way that each capillary is correctly supplied at the proper pressure (Mulvany, 1990;Segal, 2005). This part of the vascular network composed of arterioles, capillaries and venules is embedded within the organ irrigated and is called microcirculation (Davis et al, 1986;Segal, 2005;Lockhart et al, 2009). Finally, veins carry blood back to the heart through a convergent arborescence.…”

“…An external elastic lamina may also be present between the media and the adventitia or even within the media in larger vessels such as the aorta, but this structure is fragmented in small arteries and absent in arterioles (Mulvany, 1990;London et al, 1998). The number of smooth muscle cell layers decreases with decreasing vessel diameter and, in arterioles, only an unbroken monolayer of smooth muscle cells is found (Davis et al, 1986;Mulvany, 1990;Segal, 2005). In contrast, the structure of the intima is similar in all blood vessels and is formed by a smooth, continuous single layer of endothelial cells that lines the inner surface of the vessels (Mulvany, 1990).…”