[Multicenter retrospect analysis of early clinical features and analysis of risk factors on prognosis of elderly patients with severe burns]

Objective: To investigate the early clinical characteristics of elderly patients with severe burns and the risk factors on prognosis. Methods: This study was a retrospective case series study. Clinical data of 124 elderly patients with severe burns who met the inclusion criteria and were admitted to the 12 hospitals from January 2015 to December 2020 were collected, including 4 patients from the Fourth People's Hospital of Dalian, 5 patients from Fujian Medical University Union Hospital, 22 patients from Guangzhou Red Cross Hospital of Jinan University, 5 patients from Heilongjiang Provincial Hospital, 27 patients from the First Affiliated Hospital of Naval Medical University, 9 patients from the First Affiliated Hospital of Nanchang University, 10 patients from Affiliated Hospital of Nantong University, 9 patients from Tongren Hospital of Wuhan University & Wuhan Third Hospital, 12 patients from the 924th Hospital of PLA, 6 patients from Zhangjiagang First People's Hospital, 4 patients from Taizhou Hospital of Zhejiang Province, and 11 patients from Zhengzhou First People's Hospital. The patients' overall clinical characteristics, such as gender, age, body mass index, total burn area, full-thickness burn area, inhalation injury, causative factors, whether combined with underlying medical diseases, and admission time after injury were recorded. According to the survival outcome within 28 days after injury, the patients were divided into survival group (89 cases) and death group (35 cases). The following data of patients were compared between the two groups, including the basic data and injuries (the same as the overall clinical characteristics ahead); the coagulation indexes within the first 24 hours of injury such as prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time, D-dimer, fibrinogen degradation product (FDP), international normalized ratio (INR), and fibrinogen; the blood routine indexes within the first 24 hours of injury such as white blood cell count, platelet count, neutrophil-to-lymphocyte ratio, monocyte count, red blood cell count, hemoglobin, and hematocrit; the organ function indexes within the first 24 hours of injury such as direct bilirubin, total bilirubin, urea, serum creatinine, aspartate aminotransferase, alanine aminotransferase, total protein, albumin, globulin, blood glucose, triglyceride, total cholesterol, alkaline phosphatase, creatine kinase, electrolyte indexes (potassium, sodium, chlorine, calcium, magnesium, and phosphorus in blood), uric acid, myoglobin, and brain natriuretic peptide; the infection and blood gas indexes within the first 24 hours of injury such as procalcitonin, C-reactive protein, pH value, oxygenation index, base excess, and lactate; treatment such as whether conducted with mechanical ventilation, whether conducted with continuous renal replacement therapy, whether conducted with anticoagulation therapy, whether applied with vasoactive drugs, and fluid resuscitation. The analysis was conducted to screen the independent risk factors for the mortality within 28 days after injury in elderly patients with severe burns. Results: Among 124 patients, there were 82 males and 42 females, aged 60-97 years, with body mass index of 23.44 (21.09, 25.95) kg/m2, total burn area of 54.00% (42.00%, 75.00%) total body surface area (TBSA), and full-thickness burn area of 25.00% (10.00%, 40.00%) TBSA. The patients were mainly combined with moderate to severe inhalation injury and caused by flame burns. There were 43 cases with underlying medical diseases. The majority of patients were admitted to the hospital within 8 hours after injury. There were statistically significant differences between patients in the 2 groups in terms of age, total burn area, full-thickness burn area, and inhalation injury, and PT, APTT, D-dimer, FDP, INR, white blood cell count, platelet count, urea, serum creatinine, blood glucose, blood sodium, uric acid, myoglobin, and urine volume within the first 24 hours of injury (with Z values of 2.37, 5.49, 5.26, 5.97, 2.18, 1.95, 2.68, 2.68, 2.51, 2.82, 2.14, 3.40, 5.31, 3.41, 2.35, 3.81, 2.16, and -3.82, respectively, P<0.05); there were statistically significant differences between two groups of patients in whether conducted with mechanical ventilation and whether applied with vasoactive drugs (with χ2 values of 9.44 and 28.50, respectively, P<0.05). Age, total burn area, full-thickness burn area, serum creatinine within the first 24 hours of injury, and APTT within the first 24 hours of injury were the independent risk factors for the mortality within 28 days after injury in elderly patients with severe burns (with odds ratios of 1.17, 1.10, 1.10, 1.09, and 1.27, 95% confidence intervals of 1.03-1.40, 1.04-1.21, 1.05-1.19, 1.05-1.17, and 1.07-1.69, respectively, P<0.05). Conclusions: The elderly patients with severe burns had the injuries mainly from flame burns, often accompanied by moderate to severe inhalation injury and enhanced inflammatory response, elevated blood glucose levels, activated fibrinolysis, and impaired organ function in the early stage, which are associated with their prognosis. Age, total burn area, full-thickness burn area, and serum creatinine and APTT within the first 24 hours of injury are the independent risk factors for death within 28 days after injury in this population.

[Risk factors of early myocardial injury and the impact of early myocardial injury on prognosis of patients with extensive burns]

Objective: To analyze the risk factors of early myocardial injury and the impact of early myocardial injury on prognosis of patients with extensive burns. Methods: A retrospective case series study was conducted. From January 2018 to August 2022, 361 patients with extensive burns who met the inclusion criteria were admitted to Tongren Hospital of Wuhan University & Wuhan Third Hospital, including 231 males and 130 females, aged 50 (36, 58) years, with total burn area of 45% (35%, 60%) total body surface area. According to the highest level of creatine kinase isoenzyme-MB (CK-MB) within 72 h post injury, the patients were divided into early myocardial injury group (CK-MB≥75 U/L, 182 patients) and non-early myocardial injury group (CK-MB<75 U/L, 179 patients). The following data of patients in the 2 groups were collected and analyzed, including gender, age, total burn area, admission time post injury, combination with shock on admission, combination with inhalation injury on admission; the main blood test indexes such as myocardial enzyme spectrum, blood routine, liver and kidney function, and electrolytes within 72 h post injury; and treatment outcomes and fatality rate. Data were statistically analyzed with chi-square test, independent sample t test, or Mann-Whitney U test. The multivariate logistic regression analysis was conducted to screen the independent risk factors for early myocardial injury and for death in patients with extensive burns. Results: There were statistically significant differences in gender, combination with shock on admission, total burn area, and admission time post injury of patients between the two groups (with χ2 values of 6.40 and 6.10, Z values of 5.41 and 3.03, respectively, P<0.05). There were no statistically significant differences in age, combination with inhalation injury on admission of patients between the two groups (P>0.05). The CK-MB, creatine kinase, lactate dehydrogenase, α-hydroxybutyrate dehydrogenase, white blood cell count, neutrophil-to-lymphocyte ratio (NLR), alanine aminotransferase (ALT), aspartate aminotransferase, potassium, and hemoglobin within 72 h post injury were significantly higher than those in non-early myocardial injury group (with Z values of 15.40, 6.26, 7.59, 7.02, 2.64, 4.53, 4.07, 6.32, and 4.12, t=2.34, respectively, P<0.05), while the level of calcium was significantly lower than that in non-early myocardial injury group (Z=2.72, P<0.05). There were no statistically significant differences in other blood test indexes of patients between the two groups (P>0.05). The total burn area, admission time post injury, NLR and ALT within 72 h post injury were the independent risk factors for early myocardial injury in patients with extensive burns (with odds ratios of 1.03, 1.07, 1.04, and 1.02, 95% confidence intervals of 1.02-1.05, 1.00-1.11, 1.02-1.07, and 1.00-1.03, respectively, P<0.05). The fatality rate of patients in early myocardial injury group was 8.8% (16/182), which was significantly higher than 2.8% (5/179) in non-early myocardial injury group (χ2 =5.93, P<0.05). Early myocardial injury, age, combination with shock on admission, and combination with inhalation injury on admission were the independent risk factors for death in patients with extensive burns (with odds ratios of 3.60, 1.04, 6.53, and 3.14, 95% confidence intervals of 1.17-11.05, 1.01-1.07, 1.39-30.68, and 1.15-8.56, respectively, P<0.05). Conclusions: The total burn area, admission time post injury, NLR and ALT within 72 h post injury were the independent risk factors for early myocardial injury in patients with extensive burns. Patients with extensive burns with early myocardial injury have a higher fatality rate, and early myocardial injury is an independent risk factor for the patients' death.

[Clinical research on the expression of three vascular regulatory factors in different morphological regions of Marjolin ulcer and their relationship with angiogenesis]

Objective: To investigate the expressions of vascular endothelial growth factor (VEGF), hypoxia inducible factor-1 alpha (HIF-1α), and epidermal growth factor receptor (EGFR) in different morphological regions of Marjolin ulcer and their clinical relationship with angiogenesis. Methods: From January 2012 to December 2017, the patients admitted to our hospital who met the inclusion criteria were selected, including 92 patients with Marjolin ulcer [56 males and 36 females, aged (55±15) years], 100 patients with chronic non-cancerous skin ulcer [59 males and 41 females, aged (51±16) years], and 100 patients performed with other skin-related surgery [58 males and 42 females, aged (52±15) years], and they were enrolled into Marjolin ulcer group (MU), chronic non-cancerous ulcer group (CNU), and other skin surgery group (OSS) respectively. The etiology, pathogenic site, ulcer diameter, and course of patients in group MU were retrospectively analyzed. Ulcer tissue specimens from patients of group MU and group CNU and specimens of normal skin tissue attached to the tissue resected during operation from patients of group OSS were collected. The expressions of VEGF, HIF-1α, EGFR, and CD34 in the above-mentioned tissue and the surrounding normal skin, ulcer, epitheliomatous hyperplasia, and canceration areas in Marjolin ulcer tissue were detected by immunohistochemical method, and the positive expression rate and protein expression level were calculated. Data were processed with Pearson chi-square test, Mann-Whitney U test, Bonferroni method, and Bonferroni correction, and Spearman correlation analysis was used to analyze the relationship among the total protein expression levels. Results: In group MU, burns accounted for 91.3% (84/92) of the causes of patients, 44.6% (41/92) of the patients had tumors in the lower extremities, 62.0% (57/92) of the patients had skin ulcer diameter of 2.1-5.0 cm, and 75.0% (69/92) of the patients had a course of disease of more than 20 years. The positive rates of VEGF, HIF-1α, and EGFR in ulcer tissue of patients in group CNU were 41.0% (41/100), 77.0% (77/100), and 83.0% (83/100), respectively, significantly higher than those of normal skin tissue of patients in group OSS [12.0% (12/100), 45.0% (45/100), and 67.0% (67/100), χ(2)=21.589, 21.522, 6.827, P<0.01]. The positive rates of VEGF, HIF-1α, and EGFR in ulcer tissue of patients in group MU were 91.3% (84/92), 100.0% (92/92), and 100.0% (92/92), respectively, which were significantly higher than those in corresponding tissue of patients in group CNU and group OSS (χ(2)=53.372, 24.772, 17.159; 120.543, 72.777, 36.661, P<0.01). In ulcer tissue of patients in group MU, the positive expression rates of VEGF in ulcer, epitheliomatous hyperplasia, and canceration areas were significantly higher than the rate in surrounding normal skin area (χ(2)=87.120, 42.368, 89.624, P<0.01); the positive expression rates of VEGF in canceration and ulcer areas were significantly higher than the rate in epitheliomatous hyperplasia area (χ(2)=22.586, 16.060, P<0.01). In ulcer tissue of patients in group MU, the positive expression rates of EGFR in ulcer, epitheliomatous hyperplasia, and canceration areas were significantly higher than the rate in surrounding normal skin area (χ(2)=21.679, 27.600, 27.600, P<0.01), but the positive expression rates of HIF-1α in four morphological areas were similar (χ(2)=3.008, P>0.05). In ulcer tissue of patients in group MU, the protein expression levels of VEGF and CD34 in ulcer, epitheliomatous hyperplasia, and canceration areas were significantly higher than those in surrounding normal skin area (Z=-6.765, -6.819; -6.765, -6.640; -6.765, -6.819, P<0.01), the protein expression levels of VEGF and CD34 in epitheliomatous hyperplasia area were significantly lower than those in ulcer area (Z=-4.484, -5.266, P<0.01), and the protein expression levels of VEGF and CD34 in canceration area were significantly higher than those in ulcer area (Z=-6.427, -6.723, P<0.01) and epitheliomatous hyperplasia area (Z=-6.427, -6.462, P<0.01). In ulcer tissue of patients in group MU, the protein expression levels of HIF-1α and EGFR in ulcer, epitheliomatous hyperplasia, and canceration areas were significantly higher than those in surrounding normal skin area (Z=-6.819, -6.393; -6.819, -6.393; -6.819, -6.393, P<0.01), the protein expression levels of HIF-1α and EGFR in ulcer area were significantly lower than those in epitheliomatous hyperplasia and canceration areas (Z=-6.118, -5.638; -6.640, -6.393, P<0.01), and the protein expression levels of HIF-1α and EGFR in canceration area were significantly higher than those in epitheliomatous hyperplasia area (Z=-6.558, -6.819, P<0.01). In ulcer tissue of patients in group MU, the total protein expression levels of VEGF, HIF-1α, and EGFR were significantly positively correlated with the total protein expression level of CD34 (r=0.772, 0.415, 0.502, P<0.01) respectively; the total protein expression level of EGFR was significantly positively correlated with that of HIF-1α (r=0.839, P<0.01), both of which were significantly positively correlated with the total protein expression level of VEGF (r=0.531, 0.440, P<0.01) respectively. Conclusions: The expressions of VEGF, HIF-1α, and EGFR are the highest in Marjolin ulcer canceration area, and EGFR may promote angiogenesis through HIF-1α or directly increasing the expression of VEGF.

[Multicenter epidemiological investigation of hospitalized elderly, young and middle-aged patients with severe burn]

Objective: To compare and analyze the epidemiological characteristics of hospitalized elderly, young and middle-aged patients with severe burn in recent years, so as to provide reference for the prevention and treatment of elderly patients with severe burn. Methods: Relying on the entry system of epidemiological case data and biological sample of severe burn from multicenter in clinic, medical records of patients with severe burn, aged above 18, hospitalized in 8 burn wards from January 2012 to December 2015 were collected. Six hundred and fifteen patients who were more than 18 years old and less than or equal to 65 years old were included in young and middle-aged group (YM). Eighty-two patients aged more than 65 years old were included in elderly group (E). Data of age, gender, residence, education level, cause of injury, location of injury, season of injury, total burn area, occurrence and area of full-thickness burn injury, wound site, inhalation injury incidence and severity, post burn admission time, proportion of delayed resuscitation, proportion of escharectomy or tangential excision and skin grafting, preinjury systemic disease, system complication during hospitalization, length of hospital stay, outcome of treatment, and reason of abandoning treatment of patients were analyzed. Data were processed with chi-square test and Mann-Whitney U test. The odds ratios of preinjury systemic disease, system complication during hospitalization, and adverse outcome of patients in group YM were compared with those in group E. Results: (1) The majority of patients in the two groups were male, but the proportion of male patients in group YM was higher. There was statistically significant difference in gender distribution of patients between the two groups (χ(2)=18.727, P<0.001). The majority of patients in the two groups were from rural areas, but the proportion of rural patients in group E was higher. There was statistically significant difference in residence distribution of patients between the two groups (χ(2)=9.306, P=0.002). Patients in group YM mainly had secondary education, while patients in group E mainly had primary education. There was statistically significant difference in distribution of education level of patients between the two groups (χ(2)=146.797, P<0.001). (2) The most common causes of injury of patients in the two groups were both flame, but the proportion of patients with flame burn injury in group E was higher. There was statistically significant difference in distribution of cause of injury of patients between the two groups (χ(2)=25.063, P<0.001). The main locations of injury of patients in groups YM and E were respectively public place and private residence. There was statistically significant difference in location distribution of injury of patients between the two groups (χ(2)=46.313, P<0.001). The main seasons of injury of patients in groups YM and E were respectively summer and winter. There was statistically significant difference in season distribution of patients between the two groups (χ(2)=23.143, P<0.001). There was statistically significant difference in distribution of total burn area of patients between the two groups (χ(2)=25.799, P=0.002). The occurrences of full-thickness burn injury of patients in the two groups were similar (χ(2)=2.685, P=0.101), while there was statistically significant difference in area of full-thickness burn injury of patients between the two groups (χ(2)=26.702, P=0.002). There was no statistically significant difference in distribution of wound site of patients between the two groups (χ(2)=3.954, P=0.785). There were no statistically significant differences in incidence and severity distribution of inhalation injury of patients between the two groups (with χ(2) values respectively 0.425 and 0.672, P values above 0.05). (3) There was statistically significant difference in distribution of admission time of patients between the two groups (χ(2)=6.632, P=0.036), but there was no statistically significant difference in proportion of delayed resuscitation of patients between the two groups (χ(2)=1.261, P=0.261). The proportion of escharectomy or tangential excision and skin grafting of patients in group YM was 72.0% (443/615), which was significantly higher than 35.4% (29/82) of group E (χ(2)=44.498, P<0.001). The incidence of preinjury systemic disease of patients in group YM was 13.2% (81/615), which was significantly lower than 61.0% (50/82) of group E (χ(2)=108.337, P<0.001). The risk of preinjury systemic disease of patients in group E was 10.30 times of that of patients in group YM [with 95% confidence interval (CI) of 6.24-17.01, P<0.001]. During hospitalization, 59.8% (49/82) of patients in group E suffered from system complications, which was significantly higher than 36.6% (225/615) of group YM (χ(2)=16.282, P<0.001). The risk of system complication of patients in group E was 2.57 times of patients in group YM (with 95% CI of 1.61-4.12, P<0.001). The length of hospital stay of patients in group E was significantly shorter than that of group YM (U=36 735, P<0.001). There was statistically significant difference in treatment outcome of patients between the two groups (χ(2)=106.251, P<0.001). The risk of adverse outcome of patients in group E was 7.52 times of group YM (with 95% CI of 4.40-12.88, χ(2)=67.709, P<0.001). The proportion of abandoning treatment of patients in group E was significantly higher than that of group YM (χ(2)=150.670, P<0.001). The risk of abandoning treatment of patients in group E was 15.86 times of that of group YM (with 95% CI of 9.36-26.88, P<0.001). There was no statistically significant difference in distribution of reason of abandoning treatment of patients between the two groups (χ(2)=4.178, P=0.243). Conclusions: There were significant differences in the epidemiological characteristics of patients in groups E and YM. In elderly burn patients, the proportion of rural population was higher and the education level was lower. Flame burn was common and burns mostly occurred in private residences and in winter. The total burn area was slightly lower but the area of full-thickness burn injury was larger. The length of hospital stay was shorter and the proportion of surgical treatment was lower. The incidences of preinjury systemic disease and system complication during hospitalization were higher, and therefore the risks of adverse outcome and abandoning treatment were higher.

[Observation on clinical effects of recombinant human growth hormone on the treatment of children with severe burn]

Objective: To observe the clinical effects of recombinant human growth hormone (rhGH) on children with severe burn. Methods: Clinical data of 94 children with severe burn, hospitalized in our burn unit from April 2012 to December 2016, conforming to the study criteria, were retrospectively analyzed. According to the use of rhGH, children were divided into rhGH group (n=50) and control group (n=44). Children in control group received conventional treatment, while children in rhGH group received both conventional and rhGH treatment. The rhGH treatment was started 3 to 5 days post injury in dosage of 0.2-0.4 U·kg(-1)·d(-1,) by way of subcutaneous injection, and the course of treatment was (11±5) d. The plasma albumin and prealbumin levels, heart rate, alanine aminotransferase (ALT), and serum creatinine level in 2 weeks post injury, times of skin grafting operation, hospitalization time, total hospitalization treatment cost, and sepsis and death of children were compared between the 2 groups. Data were processed with independent sample t test, Mann-Whitney U test, and Fisher's exact test. Results: (1) In 2 weeks post injury, the plasma albumin level [(36±4) g/L] and prealbumin level [(94±34) g/L] of children in rhGH group were significantly higher than those in control group [(33±4) and (73±20) g/L, t=3.666, 3.401, P<0.05]. (2) In 2 weeks post injury, the heart rate of children in rhGH group was (123±11) times per minute, which was slower than (130±14) times per minute of children in control group (t=2.839, P<0.05). There was no significant difference in ALT level of children between the 2 groups (Z=0.868, P>0.05). The blood creatinine levels of children in the 2 groups were within normal range. (3) The times of skin grafting operation of children in rhGH group was 0.3±0.5, which was significantly less than 0.5±0.6 in control group (Z=2.234, P<0.05). The hospitalization time of children in rhGH group was (22±8) days, which was shorter than (28±10) days in control group (t=2.837, P<0.05). The total hospitalization treatment cost of children in rhGH group was (41±15) thousand yuan, which was significantly less than (53±25) thousand yuan in control group (t=2.878, P<0.05). (4) There were 2 cases of sepsis in control group and 1 case of sepsis in rhGH group, with no significant difference between the 2 groups (P>0.05). No children died in the 2 groups. Conclusions: rhGH treatment of children with severe burn can correct post-injury hypoproteinemia, improve cardiac function, reduce the times of skin grafting operation and hospitalization treatment cost, shorten hospitalization time, with no significant effect on kidney and liver function, sepsis, and death.

Nicotinic acetylcholine receptor-mediated synaptic potentials in rat neocortex

In the neocortex, fast excitatory synaptic transmission can typically be blocked by using excitatory amino acid (EAA) receptor antagonists. In recordings from layer II/III neocortical pyramidal neurons, we observed an evoked excitatory postsynaptic potential (EPSP) or current (EPSC) in the presence of EAA receptor antagonists (40-100 microM D-APV+20 microM CNQX, or 5 mM kynurenic acid) plus the GABA(A)-receptor antagonist bicuculline (BIC, 20 microM). This EAA-antagonist resistant EPSC was observed in about 70% of neurons tested. It had a duration of approximately 20 ms and an amplitude of 61.5+/-6.8 pA at -70 mV (n=35). The EAA-antagonist resistant EPSC current-voltage relation was linear and reversed near 0 mV (n=23). The nonselective nicotinic acetylcholine receptor (nAChR) antagonists dihydro-beta-erythroidine (DH beta E, 100 microM) or mecamylamine (50 microM) reduced EPSC amplitudes by 42 (n=20) and 33% (n=9), respectively. EPSC kinetics were not significantly changed by either antagonist. Bath application of 10 microM neostigmine, a potent acetylcholinesterase inhibitor, prolonged the EPSC decay time. EAA-antagonist resistant EPSCs were observed in the presence of antagonists of metabotropic glutamate, serotonergic (5-HT(3)) and purinergic (P2) receptors. The EAA-antagonist resistant EPSC appears to be due in part to activation of postsynaptic nAChRs. These results suggest the existence of functional synaptic nAChRs on pyramidal neurons in rat neocortex.

Carbonic anhydrase in the membrane of the endoplasmic reticulum of male rat liver

We have prepared subcellular fractions of male rat liver homogenate by the method of Lewis and Tata [Lewis, J. A. & Tata, J. R. (1973) J. Cell Sci. 23, 447-459], further purifying the membranes of the microsomal fraction by exposure to 0.01% Triton X-100 and centrifugation. We determined the purity of the fractions with marker enzymes and measured carbonic anhydrase (CA; EC 4.2.1.1) activity in intact and solubilized particulates with 18O exchange between CO2/HCO3- and water. We measured the concentration of CA by titration with a sulfonamide inhibitor, ethoxzolamide, obtaining an average value of 3.8 mumol/mg of microsomal membrane protein. The equilibrium constant for binding ethoxzolamide was 0.49 x 10(-9) M. The Km for CO2 was 1.7 mM and the turnover number was 560,000 sec-1, characterizing this as a membrane-bound, high-activity isozyme of type IV. By electron microscopy of tissue sections after staining with a cobalt precipitation technique, CA was seen in small cytoplasmic vesicles in hepatocytes and in microsomal particles and membranes. There was a sulfonamide-resistant (isozyme type III) and a sulfonamide-sensitive (isozyme type II) CA in the cytosol but none in the rapidly sedimenting endoplasmic reticulum. We conclude that there is no CA normally within the matrix of the cell endoplasmic reticulum but that the CA type III found in the microsome may have been captured from the cytosol during resealing. Thus the adult male rat hepatocyte contains CA type IV in the membrane of the endoplasmic reticulum and CA type II and CA type III in the cytoplasm.

[Pressor response induced by glutamate injection into caudal ventrolateral part of periaqueductal gray matter and its efferent pathway in brain-stem]

In urethane-anesthetized, tubocurarine-immobilized artificially ventilated rats, the following results were observed: (1) Sodium glutamate (Glu) microinjection into the caudal ventrolateral part of the periaqueductal gray matter (PAG) produced a marked rise in blood pressure. (2) This effect was attenuated by phentolamine or propranolol but not by atropine, injected bilaterally into the rostral ventrolateral medulla (RVL), indicating that this pressor response is mediated by RVL and alpha- and beta-receptors. (3) Propranolol-injection into RVL also attenuated the pressor response induced by electrical stimulation of the nucleus parabrachialis ventralis (NPV), while the pressor response initiated by injecting Glu into the same area (NPV) was not affected. Taken together with the previous findings that phentolamine blocks the pressor response produced by NPV-electrostimulation, but not of Glu-injection into NPV, the above results suggest that neurons in the caudal ventrolateral part of PAG may either send axons passing through the nucleus parabrachialis (NPB) and directly acting upon beta-receptors in RVL, or relay in NPB and act indirectly on alpha-receptors in RVL to produce the pressor response.