Autoregulatory patterns in the arteriolar network of cat mesentery

Innervation of the rat uterus at estrus: a study in full-thickness, immunoperoxidase-stained whole-mount preparations

The innervation of the nonpregnant rat uterus has been studied in histological sections, which contain only small samples of nerves and are unlikely to afford a complete picture of uterine innervation. Here we used whole-mount preparations of entire full-thickness uterine horns from nonpregnant rats in estrus to visualize autonomic or sensory nerves with peroxidase immunohistochemistry. Immunoreactivity was studied for tyrosine hydroxylase (TH)-labeled sympathetic nerves; vesicular acetylcholine transporter (VAChT), parasympathetic nerves; and substance P (SP) and calcitonin gene-related peptide (CGRP), sensory nerves. Neuropeptide Y (NPY) and nitric oxide synthase (NOS) identified more than one of these functionally distinct nerve types. Axons of all neurochemical classes entered the uterus at the mesometrium and innervated the uterine smooth muscle. The linea uteri, a dense band of longitudinal muscle opposite the mesometrium, contained more TH-, NPY-, CGRP-, and VAChT-immunoreactive axons than the remaining smooth muscle. Axons immunoreactive for NPY, SP, NOS, and VAChT formed a plexus near the circular muscle-endometrium interface. Rare TH- and NPY-immunoreactive axons and occasional CGRP-immunoreactive axons occurred close to uterine glands. Blood vessels had dense perivascular plexuses of TH- and NPY-containing axons and less dense NOS-, SP-, CGRP-, and VAChT-positive plexuses. The circular muscle plexus and glands were absent opposite the mesometrium. Uterine arterioles formed an interconnected network throughout the uterus. This article provides the first comprehensive description of the autonomic and sensory innervation of the nonpregnant rat uterus and will be a foundation for future studies on changes in uterine innervation caused by normal physiological or pathophysiological challenges.

Celiprolol exerts microvascular dilatation by activation of ?2-adrenoceptors

In order to clarify the question whether the beta 1-selective adrenoceptor antagonist celiprolol possesses vasodilating properties, isolated vascular networks were perfused with increasing concentrations of celiprolol (in a cumulative manner) ranging from 10(-8) to 10(-4) mol/l. The study was carried out using the isolated mesenteric vascular bed of the guinea pig mesenterium coli. Vascular diameters of four different vascular regions [vessels classified as G1 (585 +/- 30 microns), G2 (403 +/- 25 microns), G3 (282 +/- 27 microns) and G4 (197 +/- 13 microns)] were assessed by means of microscopic videoangiometry. Perfusion with celiprolol resulted in concentration dependent vasodilation which was more pronounced in G3 and G4 vessels. In addition, cumulative concentration-response curves were determined from responses obtained in the presence of 10(-8), 10(-7), 10(-6) and 10(-4) mol/l ICI 118,551 (a highly selective adrenoceptor antagonist). In the presence of ICI 118,551 at concentrations greater than or equal to 10(-6) mol/l, no celiprolol response could be observed. Lower concentrations of ICI 118,551 shifted the celiprolol concentration-response curve to the right in a concentration-dependent manner. Therefore, it is concluded (a) that celiprolol has a vasodilating effect, (b) that this vasodilation is produced by stimulation of beta 2-adrenoceptors and (c) that the vasodilating effect is more pronounced in smaller than in larger vessels (G3, G4 vs G1, G2).

Blood flow in rat sciatic nerve during hypotension

Laser Doppler flowmetry was utilized to examine blood flow in sciatic nerves of barbiturate-anesthetized and of unanesthetized decerebrate rats, in response to hypotension induced by graded exsanguination or by graded clamping of the descending aorta. Continuous laser Doppler flowmetry signals decreased linearly with decreasing arterial blood pressure. In anesthetized as well as in unanesthetized rats, the signal approached zero at a systemic blood pressure of 14 mm Hg or less. The results do not demonstrate autoregulation of blood flow in the rat sciatic nerve during systemic hypotension.

The microvasculature in skeletal muscle. I. Arteriolar network in rat spinotrapezius muscle

A quantitative analysis of blood flow dynamics in skeletal muscle requires a detailed picture of the microvascular network. This report presents an analysis of the arteriolar network structure in the spinotrapezius muscle of the rat. The microvasculature is visualized by injection of a carbon suspension and recorded in the form of photomicrographs with a complete reconstruction of the microvasculature on transparent overlays. The spinotrapezius muscle has several major feeding arterioles which supply blood into an extensive meshwork of interconnecting or arcading arterioles spanning the entire muscle. The connections from the arcade arterioles to the capillaries are provided by transverse arterioles, which branch from the arcades at regular intervals. Each transverse arteriole forms a single asymmetric dichotomous tree and within each muscle there is a wide range in the size of transverse arterioles. A new branching schema is proposed to describe the arteriolar network. A set of network parameters is derived and typical values of these parameters in the spinotrapezius muscle of the rat are provided.