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Biomedical subjects

E T Sutton

Publications and source records attributed to E T Sutton.

46 records · Page 3Linked to original sources
PubMed1982

Red blood cell and plasma distribution in SHR cremaster muscle microvessels.

Distribution of blood in the cremaster muscle microvasculature of spontaneously hypertensive (SHR) and Wistar-Kyoto normotensive (WKY) rats was determined by fluorescence videomicroscopy and densitometry. Bolus intra-arterial injections of fluorescein isothiocyanate (FITC)-dextran or dichlorotriazenylaminofluorescein-treated red blood cells (DTAF-RBC) produced time-concentration curves in the series-coupled segments. WKY and SHR mean arterial pressure averaged 89 +/- 6 and 125 +/- 5 mmHg, respectively. Arteriolar diameters were not different between the two groups. The smallest SHR venules (V4) and larger diameters than those of WKY (P less than 0.05), whereas V3 and V2 were not different. WKY diameters for V1 were significantly greater than those of SHR. The mean transit (t) and appearance times (ta) of both indicators were equal at the largest arteriole (A1) in both groups. In A2, A3, and A4 the t for both indicators were generally lower in SHR than in WKY rats but not significantly. The venular t were significantly greater in SHR than in WKY rats with DTAF-RBC consistently less than FITC-dextran values. The greater cross-sectional area of V4 in SHR than WKY rats would reduce flow velocity and elevate t. Dispersion (ta/t = 1.0 indicates no dispersion) of both indicators was less in WKY than in SHR. The ratios for both groups increased at V4 because ta increased more than t. Shorter circuits for red blood cells than for plasma and less plasma skimming exists in WKY than in SHR.

Animals↗
PubMed1982

Electron microscopy of selectively denervated canine carotid sinuses.

Selective denervation as used to characterize the nerve endings in the carotid sinus wall of the dog. Areas of dense innervation were identified by acetylcholinesterase histochemical technique and sampled for electron microscopic study following survival periods of 48 to 144 hours after selective neurectomies were done. Large varicosities, similar to previously described mechanoreceptor endings, showed signs of degeneration after transection of the sinus nerve, but not after cranial cervical ganglionectomy or section of the glossopharyngeal nerve proximal to its sensory ganglia. These were concluded to be endings of afferent neurons. Histochemical reactions at the fine structure level demonstrated such varicosities to be acetylcholinesterase positive. Smaller varicosities containing granulated synaptic vesicles degenerated after cranial cervical ganglionectomy was done. These were interpreted to be postganglionic sympathetic endings. This study represents an example where denervation, coupled with short survival periods, serves as a technique for studying selected areas of the peripheral nervous system.

Animals↗
PubMed1980

Microvessel mean transit time and blood flow velocity of sulfhemoglobin-RBC.

An indicator dilution technique is described for obtaining time-concentration curves subsequent to bolus injections of sulfhemoglobin red blood cells (SH-RBC), which have a deep greenish-brown color (absorption peak 620 nm vs. 542 and 564 nm for normal red cells). The series- and parallel-coupled microvessels of cat mesentery were studied. This is accomplished by means of video microscopy with a two-window intensity-sensitive video sampler system. The relationship between SH-RBC concentration in blood and optical measurement is linear. Blood flow velocities were calculated from the difference in mean transit times between two points along a vessel. When this technique is used in association with the previously reported method for determining time-concentration curves for the plasma indicator FITC-dextran the mean transit time (t) for red blood cells was less than for plasma in arterioles. The reproducibility of t and flow velocity for both SH-RBC and FITC-dextran from successive injections were reported. The mean transit time ratio of arteriolar SH-RBC to FITC-dextran averages 0.89. Blood flow velocity calculated from SH-RBC is greater than that calculated from FITC-dextran in these same arterioles. The ratio of the velocities averages 1.29.

Animals↗
PubMed1979

Frequency-dependent control of nutritional and nonnutritional circuits in the dog paw.

The neural control of blood flow and volume distribution between parallel nutritional and nonnutritional circuits has been investigated in 13 vascularly and neurally isolated dog hindpaws. The superficial and deep fibular nerves and the tibial nerve were cut and individually stimulated at frequencies of 0.1, 1, 5, 10 and 15 Hz. Increasing stimulation rates to each nerve progressively increased blood flow resistance. Vascular volume changes were determined by indicator dilution and tissue volume changes by plethysmography. The permeability surface area product of 86Rb (PS) and the capillary filtration coefficient (CFC) were determined. Superficial fibular nerve and deep fibular nerve stimulations caused progressively increased nonnutritional circuit constriction with increasing stimulation frequencies resulting in blood flow redistribution to the nutritional circuit as evidenced by increasing PS and CFC values. Tibial nerve stimulation at 0.1 Hz caused nonnutritional circuit constriction and blood flow redistribution to the nutritional circuit (PS and CFC increased). As the stimulation frequency was increased, there was progressive increase of the nutritional circuit constriction and altered blood flow distribution; i.e., CFC and PS decreased with increasing frequency of stimulation, presumably due to predominantly arterial segment resistance increase.

Animals↗
PubMed1979

Microvascular plasma velocity and indicator dispersion with hemorrhage.

The effects of stepwise hemorrhages on plasma flow velocity and indicator (FITC-Dextran) dispersion in series and parallel coupled microvascular vessels has been studied. The mesentery of cats (0.6 kg) anesthetized with Dial-Urethane was exposed and studied with a microscope equipped for fluorescense microscopy. Indicator was injected as a bolus (0.1 ml in 0.5 seconds) in a small branch of the mesenteric artery. Indicator curves were recorded from a video tape recording of the passage of the indicator by a video sampler with intensity sensitive windows. The mean transit time (t), appearance time (t(a)), peak time (t(p)), curve duration (t(E)), plasma velocity and vessel diameter changes were determined. Arterioles 68 +/- 8 micron and 35 +/- 3 micron and venules 55 +/- 6 micron constricted gradually with hemorrhage. Arterioles 20 +/- 2 micron constricted with mild hemorrhage and remained constricted with further hemorrhage. Arteriolar and venular plasma velocities decreased abruptly with mild hemorrhage and then continued to decrease gradually with further hemorrhage. Capillary flow ceased after moderate hemorrhage and was not reestablished until at least an hour after reinfusion. Arteriole t increased with hemorrhage but t increased much more in capillaries and venules. t(E) changes paralled t changes. The ratio t(a)/t was lower for venules than arterioles and both decreased with hemorrhage but the venular ratio decreased significantly more. Venular t(p)-t(a) and t(E)-t(p) increased more than arteriolar values. Hemorrhage increased indicator dispersion with the greatest effect occurring between the arteriolar and venular vessels.

Animals↗
PubMed1978

Neural control of nutritional and nonnutritional circuits in the dog hindpaw.

The neural control of blood flow and volume distribution between parallel nutritional and nonnutritional circuits has been investigated in the vascularly and neurally isolated dog hindpaw. Twelve paws were perfused by controlled pressure and ten paws were perfused by controlled flow via the cranial tibial artery. Venous outflow was measured and collected from the lateral saphenous vein. The superficial and deep fibular nerves and the tibial nerve were cut and individually stimulated, resulting in rates which at least doubled the blood flow resistance. Vascular volume changes were measured by injections of 51Cr-labeled red cells and 131I-labeled albumin. Tissue volume changes were measured by plethysmography. Capillary diffusion capacity was calculated from 86Rb extractions, and capillary filtration coefficients were determined. Superficial fibular nerve and deep fibular nerve stimulations apparently resulted in nonnutritional circuit constriction with resulting blood flow redistribution to nutritional circuits, possibly located in tissues other than the skin, e.g., adipose tissue. Tibial nerve stimulation caused no redistribution of blood flow between the two circuits presumably due to a uniform constriction of arteries and small vessel segments.

Animals↗
PubMed1976

Skeletal muscle vascular volume changes with increased venous pressure.

Dog gracilis muscles were removed, enclosed in a plethysmograph and perfused at constant inflow pressure or constant inflow. Circulating blood volumes were measured by the constant infusion technique using RBC-51Cr or albumin-131I. Control venous pressure averaged 3 mm Hg and elevations (delta PV) over the range of 5-40 mm Hg were produced. Volume changes were determined during and following delta PV by plethysmography and by changes in total muscle radioactivity. Changes in total (amount of blood in the tissue), active (circulating), and mobilized vascular volumes were calculated. Active vascular volumes and total vascular volumes increased with venous pressure increments up to 25 mm Hg and then plateaued. Active vascular volumes (indicators) increased by amounts significantly greater than the increases in total vascular volume (plethysmography). Volume changes in the constant flow groups were double those in the constant pressure groups. The mobilized active vascular volume (active vascular volume change minus total vascular volume change) consists of a volume of blood contained in vessels unattainable by the indicators during the control period but which were made available to the indicator by the delta PV. Mobilized vascular volume averaged 45% of the active vascular volume change. With venous pressure elevation there was an increase in the RBC-51Cr volume to albumin-131I volume ratio. This suggests a redistribution of red cells with respect to plasma, possibly resulting from reduced plasma skimming.

Animals↗
PubMedDate not supplied

Effects of vasodilation on plasma distribution in SHR cremaster muscle microvessels.

Alterations in the structure, number, reactivity, contractility and sensitivity of resistance vessels of hypertensive animals have been reported. If the etiology of hypertension is due to one or a combination of these factors, it could logically be expected that the distribution of blood flow from the arterial to venous circulation through parallel microcirculatory circuits could be affected. The right cremaster muscles of pentabarbital anesthetized Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) (6-8 weeks old) were exposed and prepared for fluorescent videomicroscopy. The right iliac artery was cannulated with PE-10 tubing, the tip of which was placed at the aortic bifurcation for bolus injections of FITC-dextran (70,000 molecular weight) and arterial pressure measurement. Passage of the indicator through the microcirculation was recorded on videotape during control and during vasodilation by topical application of adenosine (0.2 M). Time-concentration curves were recorded by means of dual window videodensitometry upon replay of the tape. Arterial pressure averaged 85 +/ 3 mm Hg in WKY rats and 110 +/- 5 mm Hg in SHR. Arteriolar flow velocity varied directly with small arteriolar diameter. Dilation significantly reduced the venular appearance (ta), mean transit time (t), and curve width time (tE) in WKY and SHR. The ta was significantly more reduced in SHR than WKY. This would suggest that, in WKY, dilation may have opened some new parallel circuits but principally increased flow velocity through existing circuits. In SHR, new shorter and/or higher velocity circuits were opened as evidenced by the reduced ta with the longer and/or lower velocity circuits largely unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗