Evidence from the oestrous cycle for male-induced ovulation in Bettongia penicillata (Marsupialia)

Female brush-tailed bettongs (Bettongia penicillata) housed in a breeding group of one male and one to three females had an average gestation period of 21.2 days (n = 58) and parturition was followed within 24 h by oestrus and mating. If a young was not born as a result of the mating, oestrus recurred after about 21.7 days (n = 12). From removal of pouch young to birth was 17.5 days, on average (n = 85), in females that had mated post partum, but most females that were isolated from a male before parturition returned to oestrus about 6.6 days after simultaneous removal of pouch young and return to the male (n = 9). Females housed in female-only groups appeared not to come into oestrus or to do so irregularly. These females, when returned to the male, usually came into oestrus within 10 days. These data provide evidence that, in most females of B. penicillata, ovulation does not occur in the absence of a male and that previously isolated females return to oestrus within 10 days of return to the male.

Evidence from plasma progesterone concentrations for male-induced ovulation in the brush-tailed bettong, Bettongia penicillata

Female brush-tailed bettongs, Bettongia penicillata, were housed with either an intact or vasectomized male or isolated from males in the peripartum period. Development of the quiescent corpus luteum formed at the post partum oestrus was initiated by removing the pouch young. Blood samples for analysis of plasma progesterone were collected from the females 2 days before removal of pouch young, daily for 5 or 6 days and then 2-3 times each week until 19 days after removal of pouch young. Plasma progesterone profiles were similar in pregnant and nonpregnant cycles. There was an early progesterone peak (1206 +/- 121 pg ml-1, mean +/- SEM; n = 16) between days 2 and 5 after removal of pouch young, and a second period of high concentrations (greater than 800 pg ml-1) before birth on day 17.4 +/- 0.2 (n = 16). The interval between the early peak and birth was 14 or 15 days. On five of 34 occasions, no increases in plasma progesterone concentrations occurred after removal of pouch young. On 12 of 15 occasions for 13 females that had been isolated from males post partum, plasma progesterone concentrations also remained low (less than 100 pg ml-1) and did not change after removal of pouch young. Females that showed no increases in plasma progesterone concentration after removal of pouch young had significantly lower (P less than 0.001) plasma progesterone concentrations while lactating than those females that did undergo a cycle after removal of pouch young (60 +/- 4 pg ml-1, n = 17 and 225 +/- 23 pg ml-1, n = 30, respectively). Females isolated from males post partum, and monitored until day 12 after removal of the pouch young, and that showed no increases in progesterone in this period, had ovaries that contained no corpus luteum, only corpora albicantia and numerous atretic or developing follicles. We conclude that brush-tailed bettongs are induced ovulators, a characteristic described for only one other marsupial, Monodelphis domestica, from South America.

Selective impairment of neuroendocrine and hemodynamic responses to a mu-opioid peptide in aged rats

The objective of this study was to determine if there are age-related alterations in hemodynamic and/or neuroendocrine responses to the mu-opioid receptor agonist, [D-Ala2,MePhe4,Gly(ol)5] enkephalin (DAMGO), or corticotropin releasing hormone (CRH) administered centrally. To this end, DAMGO (1-3 nmoles) or CRH (1 nmole) was injected intracerebroventricularly (icv) to freely moving young (6-8 month) and aged (24-26 month) Fischer 344 male rats. Blood pressure, heart rate (HR), and plasma concentrations of norepinephrine (NE), epinephrine (EPI), adrenocorticotropin (ACTH), and prolactin (PRL) were measured over time. Under basal conditions, NE levels were higher and blood pressures were lower in aged rats, whereas there were no significant differences in EPI, ACTH, or PRL levels. The stimulatory effect of DAMGO on blood pressure, HR, and plasma EPI and ACTH was attenuated, but the PRL response was enhanced in aged cohorts. In contrast, there were no age-related differences in the NE responses to DAMGO or CRH nor in CRH-induced increases in EPI or ACTH. The sympathoadrenal and hemodynamic effects of DAMGO were blocked by naloxone in both age groups. These results indicate that alterations in mu-opioid function with age are specific for the opioid system and do not reflect a generalized decline in central regulation of neuroendocrine and cardiovascular function.

Inhibition of c-jun causes reversible proliferative arrest and withdrawal from the cell cycle

We studied the effect of c-jun depletion in Friend murine erythroleukemia (F-MEL) cells stably transfected with a plasmid that allowed for the glucocorticoid-mediated conditional expression of c-jun antisense sequences. The c-jun cDNA used for the construction of the vector was modified so as to prevent the nonspecific targeting of junB and junD transcripts. High level and rapid induction of c-jun antisense transcripts was achieved with as little as 10(-8) mol/L dexamethasone (DEX) and resulted in a 80% to 90% reduction in c-jun protein levels. The continuous exposure of the transfected cells to DEX inhibited growth by greater than 85% over a 5-day period, whereas DEX had no effect on the growth rate of control F-MEL cells. This proliferative block was associated with a reversible accumulation of cells with a 2n DNA content. When these cells were recultured in the absence of DEX, c-jun protein rapidly reappeared and the immediate early response genes egr-1, junB, and c-myc were transiently expressed. Thus, inhibition of c-jun protein causes logarithmically growing cells to leave the cell cycle and to enter a state closely resembling, if not identical to, G0. These results underscore the importance of c-jun in maintaining cellular proliferation and provide additional evidence for the participation of proto-oncogenes in cell cycle control.

Enhancing esthetic knowledge: a teaching strategy

This article describes a teaching strategy that has been used with graduate students to enhance their esthetic knowing through representing, interpreting, and envisioning the lived experience of a caring presence in nursing practice. As students engaged in reflecting, writing, and discussion, the explicit and tacit meanings associated with a caring presence unfolded in esthetic knowing in nursing.

Taxonomic Affinities and Intra- and Interspecific Variation in Bursaphelenchus spp. as Determined by Polymerase Chain Reaction

Identification of closely related nematode species or races can be very difficult when diagnostic characters are plastic and overlapping. In this study we describe the use of polymerase chain reaction technology and direct DNA sequencing on 19 populations of Bursaphelenchus spp. to help understand their taxonomic relationships. The 5' end of the heat shock 70A gene from Caenorhabditis elegans was used as the target DNA sequence because it contains both coding and non-coding regions. The results indicate that the 19 populations could be divided into five types within B. xylophilus and four types within B. mucronatus. On a larger scale, the data revealed three distinct groups, representing B. xylophilus from North America and Japan, B. mucronatus from Japan, and "B. mucronatus" from Europe. There is sufficient difference between the European and Japanese "B. mucronatus" groups to warrant their consideration as separate species.

Stress, computer-based work monitoring and measurement systems: a conceptual overview

The design and implementation of computer-based work monitoring systems can result in changes in the organization, job and task. Electronic performance monitoring (EPM) systems are one type of change based on principles of work simplification and work rationalization. In this new work arrangement, control and coordination functions are allocated to the computer. The supervisor becomes a monitor of information and primarily provides negative performance feedback to the employee. The employee is constrained in his/her ability to use either job resources or social resources to meet the greater demands resulting from the system controlling the pace of work. It is proposed that these work arrangements provoke stress responses in employees that can result in short-term illness and potentially long-term changes in health status. Information enriched work environments are proposed as an alternative. These new work arrangements could improve job resources and social resources to manage job demands and reduce the potentially damaging stress responses. To provide a frame of reference we focus on the impact of EPM systems on the organizational and job elements involved in provoking individual stress responses. The impact of EPM systems on individual health is described using a psychosocial stress framework. Ergonomics interventions discussed include: participation in the design process; allocation of control and coordination functions between the computer and the employee; development of feedback systems; and work measurement and the development of performance appraisal systems.

Employee stress and health complaints in jobs with and without electronic performance monitoring

Current applications of electronic performance monitoring based on job design theories that consider worker performance rather than stress issues are likely to generate unsatisfying and stressful jobs (Smith et al, 1986). This study examines critical job design elements that could influence worker stress responses in an electronic monitoring context. A questionnaire survey of employees in telecommunications companies representative of each region in the United States examined job stress in directory assistance, service representative and clerical jobs with specific emphasis on the influence of electronic monitoring of job performance, satisfaction and employee health. Useable surveys were received from 745 employees representing seven operating companies and AT & T; a response rate of about 25%. The results of this survey indicated that employees who had their performance electronically monitored perceived their working conditions as more stressful, and reported higher levels of job boredom, psychological tension, anxiety, depression, anger, health complaints and fatigue. It is postulated that these effects may be related to changes in job design due to electronic performance monitoring.

Treatment of endocarditis due to Pseudomonas aeruginosa with imipenem

Therapy for endocarditis due to Pseudomonas aeruginosa is complicated by the emergence of resistance during therapy, lack of universally available synergistic antimicrobial agents, and unacceptably high morbidity and mortality rates. The authors report a case of aortic valve endocarditis due to P. aeruginosa in which resistance to piperacillin developed during combined therapy with tobramycin. Bacteriologic cure was obtained with a combination of imipenem/cilastatin and tobramycin. The authors review six other cases of P. aeruginosa endovascular infections treated with imipenem.

Nucleotide sequence of a Drosophila melanogaster gene encoding a calreticulin homologue

A Drosophila melanogaster gene encoding a homologue of the mammalian ER calcium binding protein, calreticulin, was cloned and the nucleotide sequence determined. Four exons can be identified, contained within 1700 bp of sequence, separated by introns of 124, 266 and 92 bases. The exons encode a 389 amino acid protein which may be a precursor form as it includes an N-terminal signal region of 17 residues that could potentially be cleaved to form a mature protein. The C-terminal region of the protein contains the established pattern of polyacidic clusters, common to calreticulins of other species and ends in the ER retention signal HDEL. Excluding the N-terminal signal region, the Drosophila protein amino acid sequence has a 67% identity to mammalian calreticulins and the length and acidity of the C-terminal zone in the insect protein are intermediate between higher mammalian and lower nematode values.

Effects of lithotripter-generated high energy shock waves of mammalian cells in vitro

The effects of high energy shock waves on an established human prostatic carcinoma cell line (PC-3) were investigated. HESW were administered to PC-3 cell suspensions using an electrohydraulic lithotripter (Dornier HM3). Experimental variables included the number of shocks to which the cells were exposed, spark generator potential, and the position of the cell sample in the acoustic field. Two types of cellular damage were observed: immediate cell destruction (lysis) as measured by electronic particle counting and the loss of reproductive capacity (viability) among the remaining cells as determined by colony formation assay. Over the range of the experimental variables studied, cell lysis was dependent to a greater extent on the number of shocks administered than the generator potential. Viability was affected less but was also dependent on both the generator potential and shock number. Cell lysis was strongly dependent on the position of the sample in the acoustic field with the extent of damage increasing as the sample was moved along the central axis of the shock wave from the f2 focus towards the electrodes. Possible mechanisms of damage and the relationship of the in vitro effects to the damage observed in normal tissues of patients undergoing extracorporeal lithotripsy for kidney stone disease are discussed.

A C. elegans gene encodes a protein homologous to mammalian calreticulin

The gene encoding a C. elegans homologue of the mammalian reticuloplasmin, calreticulin, was cloned and sequenced and the amino-acid sequence of its product deduced. The coding region of the gene comprises three exons separated by introns of 95 and 55 nucleotides, followed by either 158 or 279 bases of 3' non-coding sequence before putative polyadenylation signals. The precursor protein of 395 residues includes an N-terminal signal sequence of 13 residues. The C-terminus has the ER retention signal HDEL preceded by a polyacidic zone similar to known mammalian calreticulins. The sequence shows a 61% identity with mouse calreticulin, increasing to 82% in the proline-rich region of the molecule. Comparison of the C. elegans sequence with the calreticulin-related antigen RAL-1 of Oncocerca volvulus shows 73% identity, excluding the calreticulin C-terminal region. The sequence of this region differs markedly from RAL-1 where the parasite protein has a polybasic stretch and no ER retention signal. The C. elegans gene described here and designated crt-1 was mapped to a region towards the left-hand end of Chromosome V on the physical map of the genome. Southern blotting of genomic DNA indicates that in C. elegans the calreticulin homologue exists in only one form as the product of a single gene.

Effect of desipramine on norepinephrine metabolism in humans: interaction with aging

To determine whether differences in neuronal reuptake contribute to age-related changes of sympathetic nervous system activity, we compared norepinephrine (NE) release and metabolism during [3H]NE infusion and decay in six young (age 19-26 yr) and seven older (age 61-73 yr) healthy nonobese subjects. Subjects were studied on a control day and on a separate day after desipramine (DMI; 125 mg orally), a neuronal reuptake blocker. Compartmental analysis of plasma NE specific activity was used to determine several NE kinetic parameters. Plasma NE levels and NE spillover rates were higher in the elderly. Although plasma NE was unaffected by DMI in both age groups, both the metabolic clearance rate of NE from plasma and the rate of NE spillover into plasma fell in young and older groups during DMI. Furthermore, DMI dramatically lowered the mass of NE in the extravascular compartment and the rate of NE entry into the extravascular compartment. Thus neuronal uptake blockade has major effects on NE release as well as NE metabolism in humans. However, age-related differences in NE kinetics cannot be explained by differences in neuronal uptake.

Effect of an oral alpha 2-adrenergic blocker (MK-912) on pancreatic islet function in non-insulin-dependent diabetes mellitus

We used MK-912, a potent new selective alpha 2-adrenergic receptor antagonist that is active orally, to study the effect of short-term, selective alpha 2-blockade on fasting plasma glucose (FPG) and pancreatic islet function in non-insulin-dependent diabetes (NIDDM). Ten asymptomatic patients with NIDDM received either a single oral dose of MK-912 (2 mg) or placebo in a double-blind, cross-over study. B-cell function was measured by the acute insulin response (AIR) to glucose (1.66 mmol/kg intravenously [IV]) and by the AIR to arginine (5 g IV) during a hyperglycemic glucose clamp at a mean glucose level of 32.1 mmol/L to provide an estimation of maximal B-cell secretory capacity. A-cell function was estimated by the acute glucagon response (AGR) to arginine during the glucose clamp. Effective alpha 2-adrenergic blockade was apparently achieved, as there were substantial increases of plasma norepinephrine (NE) (P less than .01) and both systolic blood pressure (SBP) (P less than .01) and diastolic blood pressure (DBP) (P less than .05) after treatment with MK-912, but not after placebo. MK-912 caused a significant (P less than .05) although modest decrease of FPG that was associated with a small increase of fasting plasma insulin (P less than 0.01), C-peptide (P less than .05), and glucagon (P less than .01). FPG and hormone levels remained unchanged after placebo. MK-912 tended to increase the AIR (P = .06) and the C-peptide response (P = .07) to glucose compared with placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Hormonal and circulatory responses to chronically controlled increments in right atrial pressure

To study the time-dependent changes in the secretion of atrial natriuretic peptide (ANP) in response to chronic stimulation by controlled increments in atrial pressure, we developed methodology for precise control of right atrial pressure (RAP) in dogs by employing an externally adjustable occluder around the pulmonary artery and a servo-control system. During 7 days of servo-control of RAP at 6.3 +/- 0.1 mmHg above control levels (1.3 +/- 0.1 mmHg), the 24-h coefficient of variation in RAP was 1/45 the variation that occurred under control conditions. After 30 min of increased RAP, mean arterial pressure (MAP) was reduced from 101 +/- 4 to 84 +/- 3 mmHg in association with increments in plasma renin activity (PRA) from 0.6 +/- 0.1 to 2.5 +/- 0.9 ng angiotensin I (ANG I).ml-1.h-1 and in the plasma concentrations of ANP, arginine vasopressin (AVP), and epinephrine from 93 +/- 18 to 484 +/- 61 pg/ml, from 0.5 +/- 0.1 to 9.2 +/- 2.4 pg/ml, and from 82 +/- 27 to 585 +/- 133 pg/ml, respectively. In comparison, on day 7 of servo-control of RAP, sodium balance was achieved and MAP remained depressed (82 +/- 4 mmHg) along with sustained increments in both plasma ANP concentration (482 +/- 67 pg/ml) and PRA (1.7 +/- 0.6 ng ANG I.ml-1.h-1); on the other hand, the plasma concentrations of AVP and epinephrine returned to control levels. This quantitative study indicates that ANP secretion does not chronically adapt to stimulation by increased atrial pressure and suggests that the plasma levels of ANP achieved in heart failure markedly increase renal excretory capability and allow fluid balance to be achieved at a substantial fall in renal perfusion pressure.

Effect of epinephrine on pancreatic beta-cell and alpha-cell function in patients with NIDDM

The purposes of this study were to determine whether patients with non-insulin-dependent diabetes mellitus (NIDDM) have an enhanced glycemic response to epinephrine (EPI) and to quantitate the effect of physiological elevations of EPI on pancreatic islet function in these patients. The increment of plasma glucose (PG) in response to 45 min of EPI infusion (mean plasma EPI 2490 pM) was more than twofold greater in nine NIDDM patients than in 20 nondiabetic control subjects (mean +/- SE delta PG 3.9 +/- 0.3 vs. 1.7 +/- 0.1 mM, P less than 0.0001). The effects of EPI on beta-cell and alpha-cell function were compared in nine NIDDM patients and 9 age- and weight-matched control subjects during infusions of saline or two doses of EPI on separate days (mean plasma EPI 270, 1120, and 2490 pM). On each day, the acute insulin response (AIR) and acute glucagon response (AGR) to 5 g i.v. arginine were measured at three matched steady-state PG levels (means of 9, 14, and 29 mM). Beta-Cell sensitivity to glucose (slope of glucose potentiation) and beta-cell secretory capacity, or AIRmax (AIR at the highest clamped PG level), were calculated. In control subjects, EPI inhibited the AIR at PG concentrations of 9 and 14 mM (both P less than 0.05) but had no effect on the AIRmax, resulting in a rightward shift of the curve relating the AIR and PG and a decrease in the slope of glucose potentiation (P less than 0.01). In contrast in NIDDM patients, EPI inhibited the AIR at all PG levels, including the AIRmax (all P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Stapedius reflex decay test in diagnosis of myasthenia gravis (MG)

Stapedius reflex decay test (SRDT) was attempted in 30 patients with suspected myasthenia gravis (MG). In 43% of the sample measurement of the decay was not possible because of an audiologic abnormality, reflex threshold too high for safe testing or absence of the reflex with no obvious cause. A control group of 24 normal subjects showed a large variance and thus only a decay, after 5 minutes of stimulation, greater than 50% of the original value was considered abnormal. Out of 17 patients in whom SR decay was successfully measured, 7 (41%) had an abnormal value. Sensitivity of the test was found at 80%, specificity at 75%, when the clinical diagnosis of MG, upheld in follow-up, was taken as a criterion. The percentage of concordant abnormal findings was 50% for repetitive electrical stimulation of a peripheral nerve, 60% for positive effect of anticholinesterase drugs, 100% for presence of ACh receptor antibodies.

Time course of renal responses to greater splanchnic nerve stimulation

The objective of the present study was to describe the time courses of renal responses during renal sympathetic stimulation and to determine whether the kidney can provide a sustained response to sympathetic stimulation for 3 h. In four pentobarbital sodium-anesthetized dogs, stimulation (3.3 Hz) of a greater splanchnic nerve (GSN) on one side caused reductions in renal blood flow (RBF) and sodium excretion (UNaV) of both stimulated and contralateral-denervated kidneys, plus an increase in plasma renin activity (PRA). During continued stimulation, RBF partially recovered, but UNaV fell to less than 5% of control and PRA rose and remained at least eight times above control. In nine dogs, a single GSN was stimulated after ipsilateral adrenal medullectomy and ligation of the splanchnic circulation. The acute response to GSN stimulation was now confined to the ipsilateral kidney. Ipsilateral RBF fell by 32 +/- 10% but returned to 85 +/- 5% of control values by the end of the stimulation period. Contralateral RBF fell slowly by approximately 10%. Ipsilateral and contralateral UNaV fell to 34 +/- 10 and 43 +/- 11% of control values, respectively. PRA increased rapidly at the onset of GSN stimulation and remained at least 2.8 times control levels. After stimulation, RBF, UNaV, and PRA returned toward control levels. These results confirm the findings of others that the response of the renal vasculature to sympathetic stimulation is mainly transient. However, they additionally demonstrate a strong and sustained decrease in UNaV lasting for the total 3-h period of sympathetic stimulation.

Stimulation of renin release by hyperkalemia in the nonfiltering kidney

This study was designed to analyze the acute effects of hyperkalemia on renin release in the normal filtering kidney and the nonfiltering kidney. Plasma K was increased by acute intravenous KCl infusion. In the normal filtering kidney experiment plasma K was 5.7 vs. 3.5 meq/l. Hyperkalemia resulted in a 45% increase in renal blood flow (RBF) and a 35% increase in glomerular filtration rate (GFR) at the 120-mmHg pressure level. Renin release was significantly greater in the hyperkalemic group than in the control group (P less than 0.01) with the greatest effect over the lower pressure range. In the nonfiltering kidney experiment plasma K was 6.09 vs. 3.5 meq/l. RBF was 33% greater in the hyperkalemic than in the normokalemic group at the 130-mmHg pressure level. Renin release was also greater in the hyperkalemic group than in the normokalemic group (P less than 0.01). However, unlike the normal filtering kidney experiments, in the nonfiltering kidneys the difference in renin release was most prominent at the highest level of renal perfusion pressure. These experiments demonstrate that acute hyperkalemia can cause renal vasodilation and stimulate renin release in both filtering and nonfiltering kidney preparations and that potassium may affect renin release both through a direct effect on the juxtaglomerular cells and indirectly by affecting delivery of fluid and/or NaCl to the macula densa.

Dependence of subcellular damage on various laser beam parameters

A cw argon laser operating at the multiline UV TEM00 mode was used to create lesions in the nucleoli of fibroblast cells. Laser powers emitted through the objective were varied from 5-8 mW and laser pulse durations ranged from 50 to 600 ms. Our study showed lesion diameters ranging from 0.7 microns to 2.9 microns and an average lesion diameter of 1.77 microns. All cells were exposed to at most a laser spotsize of 2.2 microns diameter and for a laser spotsize of this diameter, we calculated that the central 18.3% of the total energy was in the central area of 0.7 microns diameter. We also found that as little as 0.3 mJ of energy could produce a lesion. No absolute threshold correlation was found between the size or type of lesion and the laser parameters used.

Amplified expression of three jun family members inhibits erythroleukemia differentiation

Several different proto-oncogenes have been shown to influence cellular differentiation. One of the most widely studied model systems has been the Friend murine erythroleukemia cell (F-MELC) line, which can be induced to undergo erythroid differentiation by a variety of chemical agents. Constitutive overexpression of either the c-myc or c-myb proto-oncogenes has been previously shown to inhibit F-MELC differentiation, whereas c-myc antisense sequences accelerate the process. To investigate the potential involvement of other proto-oncogenes and immediate early response genes in F-MELC differentiation, we studied the expression of the three known members of the jun family as well as another gene, egr-1, which, like the jun family members, is expressed as an immediate early response gene in growth factor-stimulated quiescent cells. All four genes were expressed in F-MELC, although the levels of expression and modes of regulation differed. Transfection with amplifiable c-jun, junB, or junD expression plasmids inhibited differentiation, whereas transfection with an egr-1 expression plasmid was without effect. These results indicate that jun family members play a role in mediating F-MELC differentiation. The known inhibitory effect of phorbol ester tumor promoters on F-MELC differentiation may be the result of their known stimulation of jun expression.

The leucine zipper of c-Myc is required for full inhibition of erythroleukemia differentiation

The leucine zipper motif has been observed in a number of proteins thought to function as eucaryotic transcription factors. Mutation of the leucine zipper interferes with protein dimerization and DNA binding. We examined the effect of point mutations in the leucine zipper of c-Myc on its ability to dimerize in vitro and to inhibit Friend murine erythroleukemia (F-MEL) differentiation. Glutaraldehyde cross-linking studies failed to provide evidence for homodimerization of in vitro-synthesized c-Myc protein, although it was readily demonstrated for c-Jun. Nevertheless, whereas transfected wild-type c-myc sequences strongly inhibited F-MEL differentiation, those with single or multiple mutations in the leucine zipper were only partially effective in this regard. Since the leucine zipper domain of c-Myc is essential for its cooperative effect in ras oncogene-mediated transformation, this study emphasizes the close relationship that exists between transformation and hematopoietic commitment and differentiation. c-Myc may produce its effects on F-MEL differentiation through leucine zipper-mediated heterodimeric associations rather than homodimeric ones.

Role of the central nervous system in hemodynamic and sympathoadrenal responses to cocaine in rats

These studies were undertaken to examine the contribution of central nervous system mechanisms to the cardiovascular and sympathoadrenal effects of cocaine. Changes in systolic and diastolic blood pressure, heart rate and plasma catecholamine concentrations were determined in response to cocaine injected i.a. or i.c.v. in conscious unrestrained rats. Systemically administered cocaine produced brisk, transient dose-related increases in systolic and diastolic pressure at doses of 0.05 to 5 mg/kg i.a. Plasma catecholamine concentrations increased in a dose-related manner, reaching peak levels at 5 to 10 min after i.a. cocaine injection. Only the higher doses of cocaine induced reflex vagal bradycardia that was blocked by atropine (0.4 mg/kg i.a.). Propranolol (1 mg/kg i.a.) prolonged the duration of cocaine-induced hypertension and bradycardia. Ganglionic blockade with chlorisondamine (7.5 mg/kg i.a.) antagonized completely the cardiovascular and sympathoadrenal effects of cocaine, indicating that intact ganglionic transmission is required for full expression of the autonomic responses. Antagonist drugs selective for the D-1 or D-2 dopamine receptors attenuated effects of cocaine on plasma catecholamine concentrations but not on cardiovascular parameters. Intracerebroventricular injection of cocaine (50-250 micrograms) increased systolic pressure and plasma catecholamine concentrations, providing direct evidence for an action of cocaine in the central nervous system. These results demonstrate that cocaine acts centrally to increase sympathetic outflow leading to hypertension and reflex bradycardia in conscious rats.