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PubMed1984

Dual action of morphine on cold-stimulated thyrotropin secretion in male rats.

The effect of morphine infused into 4 hypothalamic locations and the periaqueductal gray (PAG) on cold-stimulated thyrotropin (TSH) secretion was studied in male rats. Morphine decreased TSH cold-response when infused into the 3rd ventricle (1-20 micrograms/rat) or the median eminence (5 and 10 micrograms/rat). Infusions bilaterally into the anterior hypothalamus (1-10 micrograms/side) or PAG (1 and 10 micrograms/rat) were ineffective, while those given into the posterior hypothalamus (1 and 5 micrograms/side, but not 10 micrograms/side) significantly enhanced TSH cold-response. Naloxone pretreatment (2 or 5 mg/kg, s.c.) reversed the decreasing effect of morphine in the 3rd ventricle (1 microgram/rat) and the increasing effect of morphine in the posterior hypothalamus (1 microgram/side). We conclude that morphine has a dual hypothalamic action on cold-stimulated TSH secretion: an inhibition periventricularly, and a stimulation in the posterior hypothalamus.

Animals↗

PubMed1985

Attempts to antagonize the effect of histamine on the cold-stimulated thyrotropin secretion in male rats.

Histamine given directly into the 3rd ventricle inhibits the enhancement of thyrotropin secretion induced by cold-exposure (4 degrees, 30 min.) in male rats. This effect was antagonized neither by mepyramine, a H1-receptor antagonist, nor by cimetidine, a H2-receptor antagonist. Histamine would not have an indirect mechanism of action through adrenergic alpha 1- or alpha 2-receptors in rat hypothalamus, since pretreatment with neither phenoxybenzamine nor yohimbine had any effect on histamine suppressed TSH cold-response. Further, it was also tested if histamine could decrease the TSH secretion through cholinergic-, GABA-, serotonergic- or dopaminergic receptors but no results supporting such a mechanism of action were obtained. The effect of histamine was not modified by pretreatment with naloxone or desipramine either. Imidazole acetic acid, IAA, a metabolite of histamine, had no effect on cold-induced TSH secretion. It is concluded that the effect of exogenous histamine on cold-stimulated TSH secretion is not mediated through H1- or H2-receptors. Histamine may decrease brain noradrenergic activity which is important in the generation of TSH cold-response. In addition, the effect of exogenous histamine might be due to decreased endogenous histaminergic activity in rat brain.

Adrenergic alpha-Antagonists↗

PubMed1982

Effect of indoramin and propranolol on cardiovascular response to cold in hypertensive patients.

Immersion of the hand into ice water (cold-pressor test) in nine hypertensive subjects induced elevation of mean blood pressure, increase of vascular resistance in the extremities, decrease of blood flow in the extremities, and increase in heart rate. The preejection phase of systole was not altered. Indoramin and propranolol, each alone and together, attenuated the pressor and other cardiovascular responses. Submaximal exercise increased heart rate during placebo treatment, a response only partially attenuated by indoramin, propranolol, and their combination, but it did not induce changes in mean blood pressure during any of the treatments.

Adult↗

PubMed1980

Airway responsiveness to cold air and hyperpnea in normal subjects and in those with hay fever and asthma.

Multiple aspects of pulmonary mechanics were measured before and after bronchial challenges consisting of hyperpnea with cold air inhalation in 20 normal control subjects, 16 subjects with hay fever, and 44 asymptomatic asthmatics. These challenges had no effect on the lung function of the normal subjects. In the hay fever group, however, postchallenge mechanics changed a small, but significant, amount, e.g., mean decrease in forced expiratory volume in one second (FEV1) was -5.1 +/- 1.7% (SEM). The asthmatics had a much more marked response (mean fall in FEV1, -32.7 +/- 2.6%). There was considerable overlap between the responses of the normal subjects and those with hay fever, but no overlap at all between asthmatic and normal subjects. The only subjects with hay fever whose responses overlapped the asthmatic response were those who had histories of occasional episodes of wheezing. This pattern of response suggests that the use of hyperpnea and subfreezing air is a very sensitive and highly specific means of detecting increased air reactivity.

Adult↗

PubMed1999

Cold shock response of Bacillus subtilis: isoleucine-dependent switch in the fatty acid branching pattern for membrane adaptation to low temperatures.

Bacillus subtilis has developed sophisticated mechanisms to withstand fluctuations in temperature. Membrane fatty acids are the major determinants for a sufficiently fluid membrane state to ensure the membrane's function at all temperatures. The fatty acid profile of B. subtilis is characterized by a high content of branched fatty acids irrespective of the growth medium. Here, we report on the importance of isoleucine for B. subtilis to survive cold shock from 37 to 15 degrees C. Cold shock experiments with strain JH642 revealed a cold-protective function for all intermediates of anteiso-branched fatty acid biosynthesis. Metabolites related to iso-branched or straight-chain fatty acid biosynthesis were not protective. Fatty acid profiles of different B. subtilis wild-type strains proved the altered branching pattern by an increase in the anteiso-branched fatty acid content and a concomitant decrease of iso-branched species during cold shock. There were no significant changes in the fatty acid saturation or acyl chain length. The cold-sensitive phenotype of isoleucine-deficient strains in the absence of isoleucine correlated with their inability to synthesize more anteiso-branched fatty acids, as shown by the fatty acid profile. The switch to a fatty acid profile dominated by anteiso-C(15:0) and C(17:0) at low temperatures and the cold-sensitive phenotype of isoleucine-deficient strains in the absence of isoleucine focused our attention on the critical role of anteiso-branched fatty acids in the growth of B. subtilis in the cold.

Adaptation, Physiological↗

PubMed2003

Differences in properties between human alphaA- and alphaB-crystallin proteins expressed in Escherichia coli cells in response to cold and extreme pH.

It has been reported that alphaA-crystallin has greater protective effects against apoptosis in lens epithelial cells than alphaB-crystallin [Andley, Song, Wawrousek, Fleming and Bassnett (2000) J. Biol. Chem. 275, 36823-36831]. Because the alphaA-crystallin proteins are specifically expressed in the vertebrate lens, we examine the non-specific properties of both alphaA- and alphaB-crystallins in an Escherichia coli system. E. coli cells were transformed with the inducible protein expression vector pET-11a, harbouring the gene for either human alphaA- or alphaB-crystallin, and two other control plasmids, pET-1la vector alone or pGEX-2T vector encoding GST (glutathione S-transferase). These cells were exposed to various stress conditions, such as cold-shock at 4 degrees C or extremely low or high pH environments (pH 4.7 or pH 8.0) for 6 h, and survival of the host cells and the solubility of the expressed target proteins in the cytosol were examined. Under these stress conditions, the cells expressing alphaB-crystallin protein demonstrated significantly improved survival when compared with the other cells, and the expressed protein in the cytosol was almost soluble, in contrast with the alphaA-crystallin protein. Differences in the amino acid sequence between the proteins in a phenylalanine-rich region next to the N-terminal consensus alpha-crystallin domain was considered to be responsible for chaperone activity and cell survival.

Amino Acid Sequence↗

PubMed1991

Steroid-induced reduction of histamine release does not alter the clinical nasal response to cold, dry air.

In some persons, cold, dry air (CDA) provokes symptoms of rhinitis that are associated with increased levels of histamine and other inflammatory mediators in nasal lavages. Because the patterns of mediators released during the early reaction to antigen and CDA-induced rhinitis are similar, we believe that mast cell activation is part of the reaction to CDA. In view of our previous finding that 1-wk pretreatment with topical steroids reduced symptoms and mediator release in the early nasal response to antigen of allergic subjects, we examined the effect of beclomethasone dipropionate on the response to CDA. Using a double-blind, crossover design, 84 micrograms of beclomethasone or placebo were administered in each nostril twice a day to 13 volunteers for 7 days prior to CDA challenge. The reaction to CDA was monitored by measuring the levels of histamine, N-alpha-p-tosyl-L-arginine methyl ester (TAME)-esterase activity and albumin in nasal lavages before and after provocation. Overall symptom scores, as well as scores for rhinorrhea and congestion, were also obtained. Cold, dry air challenge resulted in elevation over baseline of all parameters after placebo pretreatment. After beclomethasone, a significant reduction in histamine levels, but not in TAME-esterase activity or albumin levels or in number of symptoms, was observed. These results indicate that 1-wk pretreatment with beclomethasone affects mast cells, reducing histamine release after CDA, as it did in antigen-induced rhinitis. They also indicate that histamine may not be essential for the development of the immediate nasal reaction to CDA.

Adult↗

PubMed1998

Temperature dependence of habituation of the initial responses to cold-water immersion.

The initial responses to cold-water immersion, evoked by stimulation of peripheral cold receptors, include tachycardia, a reflex inspiratory gasp and uncontrollable hyperventilation. When immersed naked, the maximum responses are initiated in water at 10 degrees C, with smaller responses being observed following immersion in water at 15 degrees C. Habituation of the initial responses can be achieved following repeated immersions, but the specificity of this response with regard to water temperature is not known. Thirteen healthy male volunteers were divided into a control (C) group (n = 5) and a habituation (H) group (n = 8). Each subject undertook two 3-min head-out immersions in water at 10 degrees C wearing swimming trunks. These immersions took place at a corresponding time of day with 4 days separating the two immersions. In the intervening period the C group were not exposed to cold water, while the H group undertook another six, 3-min, head-out immersions in water at 15 degrees C. Respiratory rate (fR), inspiratory minute volume (VI) and heart rate (fH) were measured continuously throughout each immersion. Following repeated immersions in water at 15 degrees C, the fR, VI and fH responses of the H group over the first 30 s of immersion were reduced (P < 0.01) from 33.3 breaths x min(-1), 50.5 l x min(-1) and 114 beats x min(-1) respectively, to 19.8 breaths x min(-1) 26.41 x min(-1) and 98 beats x min(-1), respectively. In water at 10 degrees C these responses were reduced (P < 0.01) from 47.3 breaths x min(-1), 67.61 x min(-1) and 128 beats x min(-1) to 24.0 breaths x min(-1), 29.5 l x min(-1) and 109 beats x min(-1), respectively over a corresponding period of immersion. Similar reductions were observed during the last 2.5 min of immersions. The initial responses of the C group were unchanged. It is concluded that habituation of the cold shock response can be achieved by immersion in warmer water than that for which protection is required. This suggests that repeated submaximal stimulation of the cutaneous cold receptors is sufficient to attenuate the responses to more maximal stimulation.

Adaptation, Physiological↗

PubMed1977

Response to cold pressor pain and to acupuncture analgesia in Oriental and Occidental subjects.

On a no treatment trial, a group of 24 oriental subjects rated cold pressor pain as significantly more painful and distressing than did a group of 24 occidental subjects. For half of the Orientals and half of the Occidentals, a second trial was conducted after acupuncture analgesia had been induced. The remaining 12 Orientals and 12 Occidentals served as no treatment controls on trial 2. Regardless of racial group, there was no difference between the pain of those experimental subjects who received acupuncture and the pain of those controls who did not. As they had on trial 1, Orientals reported significantly more pain and distress in response to ice water on trial 2. It is concluded that: (1) if acupuncture does work better for the Chinese than for other racial groups, the likely cause is a more refined patient selection procedure rather than an inherent difference in response to acupuncture; (2) evidence does not support the stereotyped view of Orientals as stoical in the face of physical pain.

Acupuncture Therapy↗

PubMed1997

Isoflurane produces marked and nonlinear decreases in the vasoconstriction and shivering thresholds.

In summary, we present a new model for evaluating thermoregulatory effects of drug administration, pregnancy, illness, etc. Specifically, we experimentally manipulated both skin and core temperatures, and subsequently compensated for the changes in skin temperature using the relationships between skin and core contributions to thermoregulatory control. We thus were able to report our results for warm- and cold-responses in terms of calculated core-temperature thresholds at a single designated skin temperature. Advantages of this model include its being nearly noninvasive and requiring relatively little core temperature manipulation. Using this technique, we have shown that the shape and magnitude of thermoregulatory impairment produced by various anesthetic drugs differs. Propofol linearly increases the sweating threshold and linearly decreases the vasoconstriction and shivering threshold. In contrast, volatile anesthetics produce a nonlinear reduction in the major cold-response thresholds, reducing the vasoconstriction and shivering thresholds disproportionately at higher anesthetic concentrations. Midazolam not only produces a different magnitude of thermoregulatory impairment, but also a novel pattern of threshold changes. Anesthetic-induced thermoregulatory impairment thus depends both on anesthetic type and dose.

Anesthetics, Inhalation↗

PubMed1994

Ventilatory and metabolic responses to cold and CO-induced hypoxia in awake rats.

Experiments were carried out in awake rats to compare the effects of ambient and CO-induced hypoxia on thermoregulation and ventilatory control. Measurements of metabolic rate (VO2), ventilation (V), shivering (EMG) and colonic temperature (Tc) were made at fixed ambient temperature (Ta) of 25, 15 and 5 degrees C. Animals were exposed to ambient hypoxia (FIO2 of 21, 17, 14, 12 and 10%) or to CO hypoxia (FICO of 0.03% in air). The results show that: (1) Both ambient and CO-induced hypoxia provoked decreases in VO2 and Tc which were more marked at low Ta values; non-shivering thermogenesis was depressed with both types of hypoxia, whereas shivering was depressed only with ambient hypoxia; (2) Ventilatory response to ambient hypoxia was blunted at low Ta values and CO-induced hypoxia did not affect ventilation. It is concluded that: (1) hypoxia affects markedly the control of Tc by altering thermogenesis: inhibition of non-shivering thermogenesis seems to result from a decrease in CaO2 whereas inhibition of shivering seems to result from a decrease in PaO2; (2) during hypoxia, ventilation is controlled by the opposite stimulation from chemoreceptors and inhibition from hypometabolism. However, as revealed by CO-induced hypoxia, another stimulatory factor may also interact with the control of breathing.

Animals↗

PubMed1980

Reflex cardiovascular responses to cold exposure of the face or foot.

Six subjects performed a breathholding maneuver during facial cooling and immersed their foot in cold water, without drugs and after the intravenous administration of propranolol plus atropine (P + A). Cardiac interval (INT), mean interval for longest consecutive 5 cycles (L5INT/5); systolic time intervals including electromechanical systole (EMS), left ventricular ejection time (LVET), pre-ejection period (PEP), and PEP/LVET; and systolic (SP) and diastolic pressures (DP) were monitored during supine rest, during apnea with a plastic bag of ice water on the face, and from 16-30th and 46-60th sec of 1-min periods of foot immersion in 4 degrees C water. P+A administration induced reduction in INT, L5INT/5, and LVET and increase in PEP, PEP/LVET, and DP. INT, L5INT/5, PEP, SP, and DP increased during facial cooling without drugs. Only the increases in INT and L5INT/5 were abolished by P+A and thus considered to result from reflexes mediated by vagal or sympathetic outflow to the heart. Reductions in INT, L5INT/5, EMS, PEP, and PEP/LVET at 16-30 sec of foot immersion without drugs were not observed after P+A; 46-60 sec responses neared resting values, however, with and without P+A. These results indicate an initial cardiac reflex response to foot immersion may be overpowered by the ventricular afterload and the foot immersion may be overpowered by the ventricular afterload and the baroreceptor response due to the increased arterial pressure.

Adult↗

PubMed1998

Arterial response during cold pressor test in borderline hypertension.

We observed previously that sympathetic activation produced by lower body negative pressure increases pulse-pressure amplification with little change in mean pressure. Whether the cold pressor test (CPT) might produce a similar hemodynamic pattern has been ignored. Ten subjects with borderline hypertension and ten age- and sex-matched normotensive controls were compared to investigate carotid-brachial pulse-pressure amplification (aplanation tonometry) and changes in brachial and carotid distensibility (echotracking technique) before and during CPT. The maneuver markedly increased blood pressure without a change in heart rate. Pulse-pressure amplification tended to disappear as a consequence of a higher increase in carotid than in brachial pulse pressure, due to an earlier return of wave reflections at the carotid site. CPT caused a significant decrease in carotid and brachial distensibility. Both results were more pronounced in controls than in borderline hypertensives. Thus CPT reduces pulse-pressure amplification. In humans, this change may greatly influence the calculation of arterial distensibility, although this point is usually minimized in animal experiments. Furthermore, in young subjects, sympathetic stimulus may induce different arterial responses, depending on the mechanism involved: reflex or global nonspecific stimulus.

Adult↗

PubMed1993

[Pressure variability in the cold-pressure response test].

The effect of the immersion of the hand in ice water for 5 minutes on the short-term variability of blood pressure (BP) and heart rate (HR) was evaluated in 10 normal subjects. Indirect finger BP was measured by a non-invasive device (Finapres). Analogue-to-digital conversion of the BP was used to determine systolic, diastolic BP and HR every 0.5 second. The equidistant sampling allowed a direct spectral analysis using a fast Fourier transform algorithm on 256 point time series of a stationary period. BP was increased (+28 mmHg for systolic BP and +13 mmHg for diastolic BP) and an increased overall variability of BP and HR was observed during the cold pressor test. The increased areas under the curve of the systolic, diastolic BP and HR spectra were documented with the selective analysis of the two main components of the spectra: the increase in the oscillations of BP and HR during the test predominated in the 70-140 mHz region (+30% for systolic BP, +24% for DBP and +21% for HR), corresponding to Mayer waves. The high-frequency (respiratory) component of BP and HR variability was unchanged. The significant increase in the 10 second period oscillations of BP could reflect the cold-induced sympathetic vasoconstriction.

Adaptation, Physiological↗

PubMed2004

Dehydrin from citrus, which confers in vitro dehydration and freezing protection activity, is constitutive and highly expressed in the flavedo of fruit but responsive to cold and water stress in leaves.

A cDNA encoding a dehydrin was isolated from the flavedo of the chilling-sensitive Fortune mandarin fruit (Citrus clementina Hort. Ex Tanaka x Citrus reticulata Blanco) and designed as Crcor15. The predicted CrCOR15 protein is a K2S member of a closely related dehydrin family from Citrus, since it contains two tandem repeats of the unusual Citrus K-segment and one S-segment (serine cluster) at an unusual C-terminal position. Crcor15 mRNA is consistently and highly expressed in the flavedo during fruit development and maturation. The relative abundance of Crcor15 mRNA in the flavedo was estimated to be higher than 1% of total RNA. The high mRNA level remained unchanged during fruit storage at chilling (2 degrees C) and nonchilling (12 degrees C) temperatures, and it was depressed by a conditioning treatment (3 days at 37 degrees C) that induced chilling tolerance. Therefore, the expression of Crcor15 appears not to be related to the acquisition of chilling tolerance in mandarin fruits. However, Crcor15, which was barely detected in unstressed mandarin leaves, was rapidly induced in response to both low temperature and water stress. COR15 protein was expressed in Escherichia coli, and the purified protein conferred in vitro protection against freezing and dehydration inactivation. The potential role of Citrus COR15 is discussed.

Amino Acid Sequence↗

PubMed2006

Quantitative reverse transcription polymerase chain reaction analysis of Vibrio cholerae cells entering the viable but non-culturable state and starvation in response to cold shock.

We performed a comparative analysis of the Vibrio cholerae strain El Tor 3083 entering the viable but non-culturable (VBNC) state and starvation after incubation in artificial seawater (ASW) at 4 and 15 degrees C respectively. To this end, we determined bacterial culturability and membrane integrity, as well as the cellular levels of 16S rRNA and mRNA for the tuf, rpoS and relA genes, which were assessed by real-time quantitative reverse transcription polymerase chain reaction (Q-RT-PCR). Bacterial cells entering the VBNC state showed a 154, 5.1 x 10(3), 24- and 23-fold reduction in the number of copies of 16S rRNA and mRNA for tuf, rpoS and relA, in comparison to exponentially growing cells. The differences were less striking between cells in the VBNC and starvation states. The mRNA for relA was selectively increased in VBNC cells (3.2-folds), whereas a 3.9-fold reduction was observed for 16S rRNA. The obtained results confirmed that key activities of the cellular metabolism (i.e. tuf representing protein synthesis, and relA or rpoS stress response) were still detected in bacteria entering the VBNC state and starvation. These data suggest that the new Q-RT-PCR methodology, based on the selected RNA targets, could be successfully exploited for the identification (rRNA) of V. cholerae and assessment of its metabolic activity (tuf, rpoS, relA mRNA) in environmental samples.

Bacterial Proteins↗

PubMed2005

Autonomic nervous system and adrenal response to cold in man at Antarctica.

OBJECTIVE: To evaluate the role of the autonomic nervous system and adrenal system in acclimatization to cold in tropical men during short or prolonged sojourns at Antarctica. METHODS: The study was carried out on volunteers of the 18th winter over team (WOT) and 19th summer team (ST) of an Indian Antarctic Expedition. The ST members were evaluated at Delhi; during voyage; and on days 7, 30, and 60 of their stay at Antarctica. Identical studies were performed in WOT members who had stayed at Antarctica for 14 months. The parameters examined included heart rate, blood pressure, oral temperature, index finger skin temperature, heart rate variability, urinary epinephrine and norepinephrine, and salivary cortisol. RESULTS: The resting heart rate and blood pressure in ST members significantly increased (P < .05) on days 7 and 30 of their stay at Antarctica and returned to baseline Delhi values by day 60. The index finger temperature declined (P < .05) on day 7 at Antarctica and remained at lower levels during the entire period of observations. Heart rate variability showed an imbalance of autonomic nervous system effects with predominance of low-frequency band on day 7 of stay and returned to Delhi values by day 60. The urinary excretion of epinephrine and norepinephrine and salivary cortisol were also increased on day 7 and declined to baseline Delhi values after 2 months of stay. Compared with the ST group, the WOT group showed a significantly higher (P < .05) resting heart rate, blood pressure, and low-frequency power and urinary excretion of norepinephrine. CONCLUSIONS: These observations suggest that Antarctic residency during austral summer results in gradual attenuation of sympathetic tone and a shift of autonomic balance toward the parasympathetic side. However, WOT members showed a predominance of sympathetic and adrenal activity compared with initial responses of ST members, suggesting deconditioning or possible resetting of the autonomic nervous system.

Adaptation, Physiological↗

PubMed2000

Accumulation and nuclear targeting of BnC24, a Brassica napus ribosomal protein corresponding to a mRNA accumulating in response to cold treatment.

Previously, we described two cDNA clones corresponding to a new family of cold regulated genes, pBnC24a and pBnC24b homologous to the human BBC1 (Breast Basic Conserved) gene. In order to further analyze the function and regulation of these two genes we have prepared antibodies against a recombinant fusion protein, MBP-BnC24A and used them to study expression at the protein level. In contrast to the increased mRNA accumulation induced by cold, immuno-blot analysis showed that the quantity of the BnC24 protein was not correlated with the accumulation of BnC24 transcripts and is identical in both control and low temperature treated (4 degrees C) plants, suggesting a translational or post-translational regulation. This was confirmed by overexpressing BnC24 in transgenic Arabidopsis thaliana plants. Despite a substantial increase in mRNA, the BnC24 protein level is unchanged. In addition, we demonstrated by subcellular fractionation and immunodetection that a significant fraction of BnC24 protein is located in the nucleus. Using a GUS fusion construction and biolistic experiments it was found that a portion of the amino terminal region is sufficient to target this protein to the nucleus. These results are consistent with the recent finding that BBC1 and its homologues code for the ribosomal large subunit protein L13. In addition they illustrate the difficulty of correlating accumulation of a given mRNA in response to a given stimulus with a biologically significant role in the adaptation to a new environment.

Journal Article↗