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Biomedical subjects

P C Harrison

Publications and source records attributed to P C Harrison.

At least 37 records · Page 2Linked to original sources
PubMed1987

Celiac cyclic blood flow pattern response to feeding and heat exposure.

Male broilers (3.0 to 3.4 kg) chronically implanted with an electromagnetic blood flow probe on the celiac artery were used to study the effect of feeding and heat exposure on celiac mean blood flow (MBF). Postprandial celiac MBF and a cyclic pattern of MBF, produced in response to feeding, were reduced (P less than .05) by a 60-min exposure to 37 C but returned during a thermoneutral (25 C) recovery period. The exact nature of this cyclic MBF phenomenon is unknown but may be related to intestinal smooth muscle activity alterations and sympathetic vasomotor tone.

Animals↗
PubMed1986

Effects of hot environments and carbonated drinking water on bone characteristics of eight-week-old broiler chicks.

Epiphyses of the femura from 8-week-old broiler chicks were examined for morphology using scanning electron microscopy and for elemental composition using energy dispersive x-ray microanalysis. Birds between the ages of 4 and 8 weeks were subjected to either 25 or 35 C environments and given tap or carbonated drinking water. The morphological appearance of the epiphyses was affected by the kind of drinking water but not the thermal environment. Elemental constituents, however, were affected by both environmental temperature and drinking water.

Animals↗
PubMed1986

Effects of thermal-induced respiratory alkalosis on blood ionized calcium levels in the domestic hen.

An experiment was conducted to determine the change with time in the blood ionized calcium concentration of hens exposed to an acute heat stress. Five hens were surgically fitted with carotid artery cannulae and placed in cages inside a temperature-controlled chamber. Blood samples were drawn before (23 C), during (35 C), and after (23 C), a 3-hr heat-stress exposure. Whole blood ionized calcium, blood gas, plasma pyruvate, and lactate were determined. Respiratory alkalosis developed 1 hr after the start of heat exposure (35 C). Approximately 1 hr later, there was a concomitant decline in blood pH as plasma lactate and pyruvate concentration increased (P less than .05). In addition, the blood ionized calcium level was reduced (P less than .05) by 19% and was negatively correlated (P less than .05) with plasma pyruvate (-.77) and lactate (-.81). These results suggest that changes in acid-base balance during heat stress reduce the blood ionized calcium level, which may in turn limit the availability of calcium for egg shell formation.

Alkalosis, Respiratory↗
PubMed1986

Alpha adrenergic regulation of celiac blood flow and plasma catecholamine response during acute heat stress in fed cockerels.

Hubbard cockerels with chronically implanted electromagnetic blood flow probes on the celiac artery were used to establish a relationship between changes in postprandial celiac mean blood flow (MBF) and plasma catecholamines during a acute heat exposure. Five min after the elevation of ambient temperature from 25 to 37 C, there were concomitant reductions (P less than .05) in celiac MBF, norepinephrine (NE), and heart rate (HR). After 50 min of heat stress, rectal temperature (Tr), respiratory rate (RR), plasma epinephrine (E), and celiac vascular resistance (CVR) were significantly greater (P less than .05) than preheat stress thermoneutral control values. During the thermoneutral recovery period, all parameters returned to values comparable to preheat exposure control with the exception of NE, which tended (P less than .1) to remain lower. To determine the role of the sympathetic nervous system in regulating postprandial celiac MBF during acute heat exposure, chronically instrumented cockerels were infused with phenoxybenzamine, an alpha-adrenergic receptor-blocking agent. Alpha-receptor blockade attenuated both postprandial intestinal hyperemia under thermoneutral conditions as well as the heat-induced reduction of postprandial celiac MBF. The results of these studies implicate the sympathetic nervous system in the regulation of postprandial celiac MBF in heat-stressed cockerels and indicate a possible alpha-adrenergic-mediated mechanism involved in postprandial intestinal hyperemia.

Adrenergic alpha-Antagonists↗
PubMed1986

The effect of high ambient temperature and hypercapnia on postprandial intestinal hyperemia in domestic cockerels.

Hubbard cockerels (2.8 to 3.6 kg) with chronically implanted electromagnetic blood flow probes placed on the celiac artery were used to determine the effect of elevated ambient temperature on postprandial intestinal hyperemia. Celiac mean blood flow (MBF) increased (P less than .05) from approximately 25 to 50 ml/min in response to feeding. When a thermoneutral temperature of 25 C was maintained, celiac MBF remained above 40 ml/min up to 210 min but fell below 25 ml/min by 300 min postprandial. In response to an acute heat exposure of 37 C, postprandial celiac MBF was reduced by approximately 50% in comparison to thermoneutral control values. Changes in celiac MBF during heat exposure were significantly (P less than .05) correlated (.60) with blood CO2 partial pressure (PCO2). To determine if flood PCO2 affected postprandial celiac MBF, cockerels were subjected to successive elevated ambient temperature and ambient CO2 treatments. Although cockerels exposed to 2.8% CO2 exhibited an increase in blood PCO2 regardless of temperature treatment, postprandial celiac MBF changes in these ambient CO2 experiments were only moderately correlated (P less than .05) with blood PCO2 (.34) but inversely correlated (-.83) with celiac vascular resistance (P less than .001). This study indicates that acute heat exposure reduces postprandial intestinal hyperemia and that this hemodynamic alteration was coincident with, but not necessarily dependent upon, changes in blood PCO2.

Animals↗
PubMed1985

Species susceptibility to the pulmonary toxicity of 3-furyl isoamyl ketone (perilla ketone): in vivo support for involvement of the lung monooxygenase system.

To explore a possible relationship between metabolism and lethality, the acute toxicity of naturally occurring perilla ketone (PK), 1-(3-furyl)-4-methyl-pentan-1-one, was examined in the uninduced mouse, hamster, rabbit, dog and pig. The LD50 (+/- SE), determined using intraperitoneal (ip) injection, for the mouse and hamster were low at 5.0 +/- .3 and 13.7 +/- .9 mg/kg, respectively. The rabbit died from an ip dosage of near 14 mg/kg and estimated ip LD50 dosages were quite high for the dog and pig, being 106 +/- 25 mg/kg and over 158 mg/kg, respectively. Dogs and the pig that died from ip injections of PK displayed varying degrees of midzonal and centrilobular liver damage and dogs also had elevated serum alkaline phosphatase and glutamic-pyruvic transaminase activities. In contrast, rodents and rabbits display only pulmonary toxicity from this agent. Cytochromes P-450 and b5 concentrations and NADPH-cytochrome c reductase activity were determined for the lung, liver and kidney of mice, hamsters, rabbits, dogs, swine, sheep and cattle. High correlation between lethality and enzyme concentration further supports the hypothesis that enzymatic bioactivation of PK is required for toxicity in all species.

Alanine Transaminase↗
PubMed1985

The effect of tap water, carbonated water, sodium bicarbonate, and calcium chloride on blood acid-base balance in cockerels subjected to heat stress.

Twenty Hubbard cockerels each weighing 2.4 kg were surgically fitted with plastic cannulae in the carotid artery and crop. A solution of either tap water (TW), carbonated water (CW), 2% sodium bicarbonate (HCO3-), or 3.5% calcium chloride (CaCl2) with pH of 7.8, 5.2, 8.0, and 7.4, respectively, was infused into the crop at .41 ml X min-1 X kg body weight (BW)-1. Blood pH, carbon dioxide partial pressure (PCO2), and respiratory rate (RR) were measured at 15-min intervals during a 90-min thermoneutral period (25 C) followed by a 90-min heat stress (37 C). Polypnea occurred in all treatments in the 37 C environment. Infusion of HCO3- increased blood pH throughout the thermoneutral and heat stress periods, and CaCl2 infusion decreased blood pH throughout the experimental periods. At thermoneutral temperature, TW and CW infusions did not affect blood pH or PCO2. During heat stress, blood pH increased in TW and CW treatments; change and final pH were significantly lower (P less than .05) for CW- compared with TW-infused birds. Although blood PCO2 decreased in all treatments with the imposition of heat stress, blood PCO2 was significantly greater (P less than .05) in birds infused with HCO3- at the end of the heat-stress period. The results demonstrate that CW treatment produced a more favorable acid-base balance during acute heat stress than TW by reducing blood pH change during thermal polypnea. Also, high levels of NaHCO3 and CaCl2 intake can produce abnormal acid-base equilibrium conditions during the heat stress-induced respiratory alkalosis.

Acid-Base Equilibrium↗
PubMed1985

Effect of carbonated water on growth performance of cockerels subjected to constant and cyclic heat stress temperatures.

Three growth trials were performed to determine the effect of carbonated water on growth performance of cockerels subjected to heat stress temperatures. In Trial 1, a 2 X 2 X 2 factorial design was used to test growth performance of Columbian crossbred cockerels between 8 and 11 weeks of age. The birds were subjected to either cyclic (day-night) heat stress (H) temperature (29 to 34 C) or cyclic (day-night) moderate (M) temperature (25 to 29 C), fed either a corn soy grower (G) diet or a 20% alfalfa diet (A), and provided with tap (TW) or carbonated (CW) drinking water. In Trial 2, a 2 X 4 X 2 factorial was used to access the effect of CW on growth performance of Hubbard cockerels between 4 and 7 weeks of age. Birds were grown in the M or H cyclic thermal environments with dietary treatments consisting of A, G, A plus 1% sodium bicarbonate (AB) and G plus 1% sodium bicarbonate (GB). In Trial 3, a 2 X 2 factorial was used to test the effect of CW on growth performance of Hubbard cockerels fed the G diet and subjected to either constant heat stress (33 C) or thermoneutral (25 C) temperatures. A 24-hr photoperiod was used in each experiment. In all three trials, heat stress reduced (P less than .05) average daily gain (ADG), feed intake, and feed efficiency (G/F).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1985

The effect of carbon dioxide on the unidirectional transport of calcium in the isolated shell gland.

An in vitro technique was developed whereby the carbon dioxide (CO2) tension of the buffer bathing the isolated shell gland could be altered without changing the pH. The isolated shell gland tissue showed a steady and linear transport of calcium. When the CO2 tension of the buffer bathing the serosal side of the shell gland tissue was increased, there was approximately an 80% enhancement (P less than .05) of the unidirectional flux of 45Ca from serosal to mucosal surfaces.

Animals↗
PubMed1984

Lack of peripheral sympathetic control of uterine blood flow during acute heat stress.

Peripheral alpha- and beta-adrenergic control of uterine blood flow (UBF) during acute heat stress of the gravid ewe was investigated. An electromagnetic blood flow probe was surgically implanted around the left miduterine artery and catheters inserted in the left carotid artery and right jugular vein in ewes between d 120 and 130 of gestation. Four or more days postsurgery, ewes were fitted with instruments to measure rectal temperature (Tr), heart rate (HR), respiratory rate (RR), blood pressure (BP) and UBF. One-half hour after instrument calibration, a 15-min thermoneutral control period was initiated with carotid artery blood samples taken at 5-min intervals for pH and PCO2 determinations. Ewes were then subjected to a heat challenge that reached 40 C at 2 h. All physiological data were recorded every 5 min as 1-min mean values. In seven experiments on five ewes, an alpha-adrenergic blocking drug, phenoxybenzamine (PB) was infused at 1 mg/min for 15 min subsequent to maximum depression of UBF. A beta-adrenergic blocking drug, propranolol (PR) was infused at .35 mg/min for 15 min in eight experiments on five ewes. Analysis of variance comparisons were made between the control period and heat stress infusion periods within the PB and PR experiments. Further comparisons were made between the start and 5, 10 or 15 min of PB or PR infusion in order to test drug effects during an acute heat stress. Rectal temperature HR, RR and arterial pH were higher (P less than .05) at the start of PR and PB infusions than during the thermoneutral control period.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

Adrenal, thyroid, and rectal temperature responses of pinealectomized cockerels to different ambient temperatures.

Pinealectomized (PX), sham-operated (PN), and control (C) cockerels were randomly assigned to three ambient temperatures (7, 23, or 37 C) at eight weeks of age. Rectal temperature (Tr) and blood were taken from birds either at mid-photophase or mid-scotophase (12L:12D) on five different days of the exposure period (0, 4, 8, 12, and 16 days). After 16 days of exposure to different ambient temperatures (Ta), birds were killed and their adrenal and thyroid glands removed. Serum T3 and T4 were measured by RIA in sera taken from PX and PN birds during both phases at each Ta. Pinealectomy depressed (P less than .05) somatic growth at each time measured independent of T3. A consistently lower Tr in PX birds held at 37 C produced an interaction (P less than .01) between pinealectomy and Ta. Across Ta, relative adrenal weights of PX cockerels (13.8 mg/100 g body weight were greater (P less than .05) than the PN and C average (12.7 mg/100 g body weight). There was an interaction (P less than .05) between pinealectomy and ambient temperature on thyroid weight; PX cockerels had smaller thyroids at 23 C and larger thyroids at 37 C than comparable controls. The PX cockerels had an average T3 concentration of 370.6 ng/100 ml compared to 350.5 ng/100 ml for PN birds. The hot environment (37 C) markedly depressed (P less than .01) serum T3 concentrations independent of surgical treatment. In PX cockerels, decreased body weights, lower Tr, and general adrenal enlargement indicate that the avian pineal gland is involved in endocrine function and maintenance of body temperature as well as normal somatic growth.

Adrenal Glands↗
PubMed1980

The effect of pinealectomy on metabolism and somatic growth of immature cockerels.

Fifty-four 1-day-old Single Comb White Leghorn cockerels were randomly assigned to 18 brooder cages across three surgical treatments, pinealectomy (PX), sham-operated (PN), and non-operated controls (C). Pinealectomy and sham-operations were performed at 9 days of age. The birds were maintained for 28 days, during which time body weight, feed consumption, and oxygen consumption were measured. All parameters were similar for all treatments during the week before surgery. During the first week after surgery, the PX birds had a lower (P less than .05) oxygen consumption and lowered (P less than .05) body weight gains compared to PN and C birds. Shortly after recovering from surgery, the PX birds became very docile and engorged their crops. This unusual behavior was not seen in the PN or C birds. By the second week after surgery, the oxygen consumption was similar for all treatments. At 21 days of age the PX birds had a significantly (P less than .05) lower body weight compared to the PN and C birds.

Animals↗
PubMed1979

Caloric value of cardiac response to hot environments.

Single Comb White Leghorn hens were placed in a controlled temperature chamber, initially at 26 C and subsequently raised to 35 C. Recordings of the surface and rectal temperatures, respiratory rate, heart rate, and oxygen consumption were made at the 26 C basal temperature and compared with those made at the 35 C ambient temperature. Sequential doses of saline and atropine were injected following the thermoregulatory response of birds to 35 C. The thermal challenge resulted in an average increase of 53 breaths per minute in the respiratory rate during the pre-injection period at 35 C and rose steadily to the end of the thermal challenge. The saline elicited no effects on any parameter measured; however, the atropine resulted in a mean increase of 62 beats per minute in the heart rate. There was no difference in the pre-atropine heart rate at 35 C and the basal heart rate at 26 C. Following the atropine induced increase in heart rate there was a 13% increase in energy expenditure. Thermal-bradycardia in hot environments may represent a first line of defense against hyperthermia by reducing the added heat load.

Adaptation, Physiological↗
PubMed1977

Influence of gonadotropic releasing hormone, luteinizing hormone and pineal extracts on testes of immature cockerels.

Two, seven, and ten-day-old S.C.W.L. cockerels were injected with pineal extract (PE), gonadotropic releasing hormone (GnRH) and luteinizing hormone (LH), alone or in combination, to determine the effect of PE on the action of exogenous GnRH and LH on the testis in immature cockerels. Radioactive phosphorus (P-32) uptake by the testis was used as an assay for gonadotropic activity. GnRH had no effects on cockerels aged two days. However, LH caused increased P-32 uptake compared to the saline control at this age. In seven- and ten-day-old cockerels, PE in combination with GnRH resulted in lower P-32 c.p.m./g. of testis compared to the non-PE treated birds at the same doses of GnRH. On the other hand, PE did not cause any decrease in testis response to LH. These results indicate that PE is acting to inhibit release of gonadotropins by GnRH.

Animals↗