Systemic hypoxia (SHx) produces microvascular inflammation in mesenteric, cremasteric, and pial microcirculations. In anesthetized rats, SHx lowers arterial blood pressure (MABP), which may alter microvascular blood flow and microvascular Po(2) (Pm(O(2))) and influence SHx-induced leukocyte-endothelial adherence (LEA). These experiments attempted to determine the individual contributions of the...

The vasoactive properties of potassium were assessed in the microcirculation of the hamster cremaster muscle and the muscular and epithelial portions of the hamster cheek pouch. Tissues were transilluminated and suffused with a physiological salt solution whose potassium concentration varied from 0 to 20 mM. Vessel diameters were measured and normalized as a percent of the control diameter (+/-...

Inducible nitric oxide synthase (iNOS) participates in many pathological events, and selective inhibition of iNOS has been shown to reduce ischemia-reperfusion (I/R) injury in different tissues. To further confirm its role in this injury process, I/R injury was observed in denervated cremaster muscles of iNOS-deficient (iNOS-/-) and wild-type mice. After 3-h ischemia and 90-min reperfusion, blo...

Nitric oxide (NO) from Ca(2+)-dependent neuronal nitric oxide synthase (nNOS) in skeletal muscle fibers may modulate vascular tone by a cGMP-dependent pathway similar to NO derived from NOS in endothelial cells (eNOS). In isolated fast-twitch extensor digitorum longus (EDL) muscles from control mice, cGMP formation increased approximately 166% with electrical stimulation (30 Hz, 15 s). cGMP lev...

Microvascular hematocrit and its possible relation to oxygen supply were systematically examined. We studied the red cell volume fraction (hematocrit) in arterial blood and in capillaries under a variety of circumstances. Control capillary hematocrit averaged 10.4 +/- 2.0% (SE) and arteriolar (14.2 micrometer ID) hematocrit averaged 13.9 +/- 1.2% in cremaster muscles of pentobarbital-anesthetiz...

Segal, Steven S., Suzanne E. Brett, and William C. Sessa. Codistribution of NOS and caveolin throughout peripheral vasculature and skeletal muscle of hamsters. Am. J. Physiol. 277 (Heart Circ. Physiol. 46): H1167–H1177, 1999.—In isolated cell systems, nitric oxide synthase (NOS) activity is regulated by caveolin (CAV), a resident caveolae coat protein. Because little is known of this interactio...

A myogenic vasoconstriction may amplify the effects of circulating vasoconstrictors. In cremaster arterioles, the contribution of a myogenic component to the constriction on intravenous infusion of norepinephrine (NE) or angiotensin II (Ang II) was studied. Second, the role of endothelium-derived nitric oxide (NO) in the control of these myogenic constrictions and its site of action in the resi...