Differences in EDNO contribution to arteriolar diameters at rest and during functional dilation in striated muscle

1993 ◽  
Vol 265 (1) ◽  
pp. H146-H151 ◽  
Author(s):  
R. L. Hester ◽  
A. Eraslan ◽  
Y. Saito
Keyword(s):  
Striated Muscle ◽  
Physiological Role ◽  
Second Order ◽  
Muscle Stimulation ◽  
Third Order ◽  
First Order ◽  
Before And After ◽  
Arteriolar Vasodilation ◽  
Arteriolar Diameter

This study was designed to determine the physiological role of endothelium-dependent nitric oxide (EDNO) in the control of arteriolar diameter during rest and muscle stimulation. Diameters of first-, second-, and third-order arterioles in the superfused hamster cremaster muscle were measured before and throughout 1 min of field stimulation before and after inhibition of EDNO release. ENDO inhibition by intravenous N omega-nitro-L-arginine methyl ester (L-NAME) significantly attenuated the arteriolar vasodilation in response to 1 microM acetylcholine. First-order arterioles averaged 65 +/- 5 microns at rest and dilated to 86 +/- 6 microns during muscle stimulation (n = 9), second-order arterioles averaged 45 +/- 6 microns and dilated to 72 +/- 3 microns during muscle stimulation (n = 6), with third-order arterioles averaging 29 +/- 2 microns, and dilating to 53 +/- 3 microns during muscle stimulation (n = 7). EDNO inhibition significantly decreased both the resting diameter of first-order arterioles (57 +/- 4 microns) and functional dilation (68 +/- 3 microns; P <0.05). EDNO inhibition had no effect on the resting diameter of second-order arterioles (45 +/- 5 microns) yet significantly attenuated the functional dilation (64 +/- 4 microns; P < 0.05). EDNO inhibition had no effect on either the resting diameter of third-order arterioles (30 +/- 2 microns) or the functional dilation (49 +/- 2 microns).(ABSTRACT TRUNCATED AT 250 WORDS)

Functional hyperemia in striated muscle is reduced following blockade of ATP-sensitive potassium channels

1996 ◽  
Vol 270 (5) ◽  
pp. H1649-H1654 ◽  
Author(s):  
Y. Saito ◽  
M. McKay ◽  
A. Eraslan ◽  
R. L. Hester
Keyword(s):  
Potassium Channels ◽  
Topical Application ◽  
Muscle Stimulation ◽  
Functional Hyperemia ◽  
Cremaster Muscle ◽  
Third Order ◽  
First Order ◽  
The Third ◽  
Arteriolar Diameter

This study was designed to determine the role of ATP-sensitive potassium channels in the control of the arteriolar diameter during functional hyperemia. The hamster cremaster muscle was prepared for in vivo microscopy and stimulated electrically for 1 min before and after topical application of 10 microM glibenclamide to block ATP-sensitive potassium channels. Glibenclamide treatment resulted in a small, though not significant, decrease in resting arteriolar diameter (P > 0.05). Glibenclamide almost completely inhibited the vasodilation of the first-order and the third-order arterioles in response to topical application of 1 microM cromakalim (P < 0.05). During muscle stimulation, the first-order arterioles dilated from 69 +/- 3 to 89 +/- 3 microns (n = 7), and the third-order arterioles dilated from 16 +/- 1 to 35 +/- 2 microns (n = 7). In this set of experiments glibenclamide treatment resulted in a significant decrease (approximately 4 microns) in the resting diameters of the first-order arterioles, but had no significant effect on the resting diameter of third-order arterioles. Glibenclamide treatment significantly attenuated the vasodilation associated with muscle contraction to 72 +/- 3 and to 21 +/- 3 microns, respectively (P < 0.05). These results suggests that ATP-sensitive potassium channels are an important mediator in the vasodilatory response to muscle stimulation in the hamster cremaster muscle.

Sodium hyperosmolarity of intestinal lymph causes arteriolar vasodilation in part mediated by EDRF

1993 ◽  
Vol 265 (1) ◽  
pp. H323-H328 ◽  
Author(s):  
J. M. Steenbergen ◽  
H. G. Bohlen
Keyword(s):  
Oleic Acid ◽  
Second Order ◽  
First Order ◽  
Acid Absorption ◽  
Intestinal Lymph ◽  
Relaxing Factor ◽  
Endothelium Derived Relaxing Factor ◽  
Arteriolar Vasodilation ◽  
Dose Dependent

This study evaluated 1) the effect of increased submucosal lymph osmolarity on the regulation of first-order (1A) and second-order (2A) intestinal arterioles and 2) the role of endothelium-derived relaxing factor (EDRF) in hypertonic-induced vasodilation. Increasing the submucosal lymph osmolarity from 280 to 400 mosM, in increments of 30 mosM, resulted in a dose-dependent dilation of 1A and 2A. A submucosal lymph tonicity of 340 mosM, as occurs during glucose and oleic acid absorption, caused dilation of 1A (118%) and 2A (124%) equivalent to that during absorptive hyperemia. The dilation caused by 400 mosM mannitol (137%) was similar to that with 340 mosM NaCl (131%) and approximately 70% of that with 400 mosM NaCl (152%). After EDRF blockade, the responses to sodium hypertonicity decreased by about one-half; blockade reduced mannitol-induced dilation by 22%. These results indicate that sodium hypertonicity, as occurs during absorption, can play a major role in absorptive hyperemia, and about one-half of the dilation is related to a sodium-coupled release of EDRF.

Role of EDRFs in the control of arteriolar diameter during increased metabolism of striated muscle

1994 ◽  
Vol 267 (1) ◽  
pp. H195-H200 ◽  
Author(s):  
Y. Saito ◽  
A. Eraslan ◽  
R. L. Hester
Keyword(s):  
Sodium Nitroprusside ◽  
Striated Muscle ◽  
Distal Portion ◽  
Distal Region ◽  
Red Cell ◽  
First Order ◽  
Cell Velocity ◽  
Red Cell Velocity ◽  
Arteriolar Vasodilation ◽  
Arteriolar Diameter

This experiment was designed to determine the role that the release of endothelium-derived relaxing factors (EDRFs), endothelium-derived nitric oxide (EDNO), or prostaglandins have in the control of arteriolar vasodilation during an increased metabolic rate in striated muscle. A silicone stopcock grease dam was placed across the distal portion of the cremaster muscle of pentobarbital-anesthetized hamsters to localize the application of the metabolic stimulator 2,4-dinitrophenol (DNP). Application of DNP (10 mM) to the distal region resulted in significant increases in red cell velocity (from 6 +/- 1 to 10 +/- 2 mm/s) and arteriolar diameter (from 75 +/- 3 to 91 +/- 5 microns) (P < 0.05; n = 6) in the first-order arterioles located approximately 11 mm upstream from the silicone dam. Administration of N omega-nitro-L-arginine methyl ester (L-NAME; 2 mg iv) resulted in significant vasoconstriction of the first-order arterioles and a significant decrease in the vasodilator response to acetylcholine (1 microM). Addition of sodium nitroprusside (380 microM) to the superfusion solution during L-NAME treatment resulted in a return of arteriolar diameter to control levels. DNP treatment during L-NAME and sodium nitroprusside treatment did not inhibit the arteriolar vasodilation [75 +/- 3 to 87 +/- 4 microns (P > 0.05)] after a significant increase in red cell velocity from 7 +/- 1 to 11 +/- 1 mm/s. Before indomethacin treatment, DNP treatment resulted in an increase in arteriolar diameter from 72 +/- 3 to 90 +/- 3 microns, preceded by an increase in red cell velocity from 6 +/- 1 to 10 +/- 1 mm/s. (ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for general base catalysis by protic solvents in a kinetic study of alcoholyses and hydrolyses of 1-(phenoxycarbonyl)pyridinium ions under both solvolytic and non-solvolytic conditions

2009 ◽  
Vol 74 (1) ◽  
pp. 43-55 ◽  
Author(s):  
Dennis N. Kevill ◽  
Byoung-Chun Park ◽  
Jin Burm Kyong
Keyword(s):  
Second Order ◽  
Base Catalysis ◽  
Substitution Reactions ◽  
Third Order ◽  
Methoxy Derivative ◽  
First Order ◽  
General Base ◽  
Protic Solvents ◽  
Kinetics Of ◽  
Pyridinium Ions

The kinetics of nucleophilic substitution reactions of 1-(phenoxycarbonyl)pyridinium ions, prepared with the essentially non-nucleophilic/non-basic fluoroborate as the counterion, have been studied using up to 1.60 M methanol in acetonitrile as solvent and under solvolytic conditions in 2,2,2-trifluoroethan-1-ol (TFE) and its mixtures with water. Under the non- solvolytic conditions, the parent and three pyridine-ring-substituted derivatives were studied. Both second-order (first-order in methanol) and third-order (second-order in methanol) kinetic contributions were observed. In the solvolysis studies, since solvent ionizing power values were almost constant over the range of aqueous TFE studied, a Grunwald–Winstein equation treatment of the specific rates of solvolysis for the parent and the 4-methoxy derivative could be carried out in terms of variations in solvent nucleophilicity, and an appreciable sensitivity to changes in solvent nucleophilicity was found.

Panicle, spikelet, and floret development in orchardgrass (Dactylis glomerata)

1993 ◽  
Vol 71 (4) ◽  
pp. 523-532 ◽  
Author(s):  
Joanna Fraser ◽  
Eric G. Kokko
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Unique Feature ◽  
Dactylis Glomerata ◽  
Bilateral Symmetry ◽  
Second Order ◽  
Third Order ◽  
First Order ◽  
Lateral Branches ◽  
Scanning Electron

The initial stages of panicle, spikelet, and floret development in field-grown 'Kay' orchardgrass were examined using scanning electron microscopy. Spikelets arose from a complex multilevelled sequence of initiation from branch apices. Spikelets developed indirectly in a two-tiered progression: (i) an acropetal and basipetal sequence of first order, second-order, and third-order inflorescence apices, and (ii) an acropetal development within subclusters of higher-order lateral branch inflorescence apices. The panicle had the unique feature of dorsiventrality as well as bilateral symmetry. The basal apex from first-order, second-order, or third-order apices developed on the same side of the main axis as the first-order apex. The two glumes subtending each spikelet primordium developed alternately and acropetally. Development and initiation of florets within spikelets was basipetal within the panicle, basipetal within clusters and subclusters of spikelets on lateral branches, and acropetal within spikelets. Within florets, paleas developed later than lemmas. Key words: Dactylis glomerata, cocksfoot, scanning electron microscopy, development, panicle.

Characteristics and origin of myogenic response in isolated gracilis muscle arterioles

1994 ◽  
Vol 266 (3) ◽  
pp. H1177-H1183 ◽  
Author(s):  
D. Sun ◽  
G. Kaley ◽  
A. Koller
Keyword(s):  
Pressure Range ◽  
Perfusion Pressure ◽  
Gracilis Muscle ◽  
Tetraacetic Acid ◽  
Flow Conditions ◽  
Third Order ◽  
Before And After ◽  
Physiological Pressure ◽  
Arteriolar Diameter ◽  
Intravascular Pressure

Responses to changes in intravascular pressure of isolated rat gracilis muscle arterioles were investigated under no-flow conditions. First-, second-, and third- order arterioles were isolated and cannulated. Vascular diameters were measured with an image-shearing device and then recorded. In response to the step increases in perfusion pressure (from 20 to 160 mmHg, by 10- or 20-mmHg steps) arterioles constricted and developed active tone. For example, at 100, 80, and 50 mmHg pressure the steady-state active diameters of 1st-, 2nd-, and 3rd-order arterioles were 76.9 +/- 1.6, 32.3 +/- 1.1 and 22.3 +/- 3.2 microns, respectively. At the same perfusion pressure, by use of a Ca(2+)-free solution (ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid; 1 mM) containing sodium nitroprusside (SNP; 10(-4) M), the passive diameters (PD) of these vessels were 161.8 +/- 3.2, 76.0 +/- 1.7, and 47.6 +/- 2.2 microns. The negative slopes of the pressure-diameter curves indicate that in the physiological pressure range an inverse relationship exists between the arteriolar diameter and intravascular pressure. The maximum constriction expressed as a percent of PD was similar in the various sized arterioles (approximately 60%) but was reached at lower pressures in the smaller vessels. The vasoactive function of endothelium and vascular smooth muscle was assessed by the responses of arterioles to acetylcholine (ACh; 10(-6) M) and SNP (5 x 10(-8) M) before and after removal of the endothelium with air. After removal of the endothelium, dilation to ACh was abolished while dilation to SNP was retained.(ABSTRACT TRUNCATED AT 250 WORDS)

A Note on Homogeneous Dendrites

1968 ◽  
Vol 11 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Z. A. Melzak
Keyword(s):  
Branch Point ◽  
Rooted Tree ◽  
Second Order ◽  
Third Order ◽  
First Order ◽  
Graph Theoretic ◽  
Order Branch

In graph - theoretic terms a homogeneous p-dendrite, p ≥ 2, is defined as a finite singly-rooted tree in which the root has valency 1 while every other vertex has valency 1 or p. More descriptively, a homogeneous p-dendrite may be imagined to start from its root as the main, or 0th order, branch which proceeds to the first - order branch point where it gives rise top first - order branches. Each of these either terminates at its other end (which is a second-order branch point) or it splits there again into p branches (which are of third order), and so on. The order of the dendrite is the highest order of a branch present in it. For completeness, a 0-th order dendrite is also allowed, this consists of the 0-th order branch alone.

Second-Order Backward Blocking and Unovershadowing in Human Causal Learning

2002 ◽  
Vol 49 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Jan De Houwer ◽  
Tom Beckers
Keyword(s):  
Higher Order ◽  
Second Order ◽  
Causal Learning ◽  
First Order ◽  
Human Causal Learning ◽  
Before And After ◽  
Causal Status

Abstract. De Houwer and Beckers (in press , Experiment 1) recently demonstrated that ratings about the relation between a target cue T2 and an outcome are higher when training involves CT1+ and T1T2+ followed by C+ trials than when training involves CT1+ and T1T2+ followed by C- trials. We replicated this study but now explicitly asked participants to rate the causal status of the cues both before and after the C+ or C- trials. Results showed that causal ratings for T2 were significantly higher after C+ trials than before C+ trials and that T2 received significantly lower ratings after C- trials than before C- trials. The results thus provide the first evidence for higher-order unovershadowing and higher-order backward blocking. In addition, the ratings for T1 revealed that first-order backward blocking (i.e., decrease in ratings for T1 as the result of C+ trials) was stronger than first-order unovershadowing (i.e., increase in ratings for T1 as the result of C- trials).

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