Risk factor knowledge, status, and change in a community screening project.

This report describes a community-based cardiovascular risk-reduction program which targeted high-risk individuals. A total of 1,471 individuals participated and were screened for blood pressure, fasting serum cholesterol, blood glucose level, and appearance of the serum. These individuals also completed a questionnaire regarding their knowledge of heart disease. Overall, 522 (35.5%) individuals had a cholesterol level of 240+ mg/dl; 261 (17.7%) had hypertension; 118 (8%) had a glucose level of 120+ mg/100 ml blood; 266 (18.1%) smoked; and the serum was evaluated as "turbid" or "lipemic" in 105 (7.1%). Therefore, of the 1,471 individuals examined, 733 (49.8%) could be considered "at risk" due to the presence of one or more risk factors. Interestingly, 73% of respondents knew their blood pressure, whereas only 15% and 12%, respectively, knew their cholesterol and glucose levels. Eighty percent of the sample knew that smoking, hypertension, and cholesterol were risk factors, but only 50% of the sample identified diabetes as an independent risk factor. Contrary to expectation, knowledge of heart disease and diabetes was not related to either initial level or change in cholesterol at 18-month retest. Overall, these results indicate that a community screening program can identify high risk individuals at a relatively low cost, and that knowledge of risk factors and disease is not related to initial risk status or self-initiated change in risk status.

Auditory startle in normotensive and hypertensive rats.

In the present experiment auditory startle was examined in male and female rats of the spontaneously hypertensive (SHR) and Wistar-Kyoto normotensive (WKY) strains and borderline hypertensive rats (BHR) derived from cross-breeding SHR females with WKY males. The magnitude of auditory startle declined over trials and was significantly higher in WKYs than in both SHRs and BHRs which did not differ from each other. These data add to an increasing body of literature concerning behavioral differences between hypertensive and normotensive rats and are discussed as they relate to the possible strain differences in either behavioral reactivity or tonic fear.

A comparison of biofeedback-assisted cardiodeceleration in type A and B men: modification of stress-associated cardiopulmonary and hemodynamic adjustments.

The primary purpose of this experiment was to examine the cardiac effects of instructions and biofeedback to reduce heart rate during both rest and a behavioral stressor. A second purpose was to assess respiratory, hemodynamic, and metabolic function in conjunction with heart rate. A final aim was to compare the effects of biofeedback on Type A and B men. Type A subjects fell in the upper 10% of the distribution of Jenkin's Activity Survey scores and Type B subjects fell in the lower 10%. Subjects experienced one of three instructional sets during an initial session: instructions to reduce heart rate with biofeedback; instructions to reduce heart rate without biofeedback; and instructions to sit quietly. During a second session, all subjects received identical instructions prior to the behavioral stressor. Heart rate, pulmonary gas exchange, and ventilation were measured breath-by-breath. During the first session, the groups did not differ in any measured parameter, but Type As had higher heart rates than did Type Bs across all conditions. During the second session, subjects given instructions to reduce heart rate with and without biofeedback did not differ in heart rate; as expected, however, both of these groups had smaller increases in heart rate than did the control group. Interestingly, the tachycardia of the control group occurred without an increase in oxygen consumption, indicating a cardiac-metabolic dissociation in this group. The modification of heart rate without a concomitant change in metabolism is important in understanding the association between cardiac and metabolic function.

Is the hypertensive rat really hyperreactive?

This study investigated the behavior of hypertensive-prone and nonhypertensive-prone rat strains to see whether there are differences in behavioral reactivity to environmental stimulation. Of primary interest was general activity, because investigators have assumed it to be an index of reactivity to environmental stimulation and to be correlated with the elevation of blood pressure in spontaneously hypertensive rats (SHR) but not in normotensive Wistar-Kyoto (WKY) rats. Therefore, general activity was assessed in SHRs and WKYs as a function of walking and rearing in an open field (Experiments 1 and 2) and crossings in a shuttlebox test (Experiments 3, 4, and 5). Activity was assessed under a constant level of environmental stimulation in the open field (Experiment 1) and shuttlebox (Experiment 3) or under varying degrees of stimulation in the open field (Experiment 2) and shuttlebox (Experiments 4 and 5). In the open field and the shuttlebox, SHR activity was above WKY activity when the degree of environmental stimulation was constant. However, when stimulation was manipulated, the SHR activity level was similar for all intensity levels, while the WKY activity was inversely related to stimulus intensity. These results suggest that while the SHRs may generally be more active than WKYs, WKYs display a greater behavioral reactivity to environmental stimulation than SHRs.

Increased secretion of vasopressin and adenosine 3',5'-monophosphate from hypothalamic-posterior pituitary units of spontaneously hypertensive rats.

To determine if the increased vasopressin (AVP) levels observed in the blood and urine of spontaneously hypertensive rats (SHR) are a response to peripheral factors that may influence AVP release or are a consequence of altered hypothalamic-neurohypophysial activity, AVP release from hypothalamic-neurohypophysial units was studied using an in vitro perifusion system. Spontaneous and 30 mM K+-stimulated AVP release was significantly greater from tissue of SHR rats than from those of WKYN. Adenosine (10(-5) M) added to the perifusion medium increased AVP release into the perifusate in both strains, even through AVP release into the perifusate was greater in tissue of SHR rats. Measurement of AVP content revealed that hypothalamic AVP was lower in SHR rats, whereas the neural lobes of the SHR contained a significantly higher concentration of AVP compared to the tissue of WKYN rats. In addition, exposing tissue from SHR rats to 30 mM K+ stimulated an increase in cAMP release into the perifusate, whereas tissue from WKYN rats did not increase cAMP release above basal level. These data suggest that central nervous system-mediated hyperresponsiveness is the basis for the increased AVP secretion that occurs in the SHR rat and are consistent with reports of a hypersensitive hypothalamic-anterior pituitary axis in these animals.

Developmental aspects of 2-way shuttlebox avoidance in the spontaneously hypertensive and normotensive rat.

In experiment I, male and female rats from the spontaneously hypertensive (SHR) and Wistar-Kyoto (WKYN) normotensive strains were given I session of 2-way shuttlebox avoidance training at 25-26, 35-36, or 45-46 days of age. The avoidance training was preceded by a pretest which consisted of 10 presentations of the compound conditional stimulus alone in order to assess any differential tendency of the 2 strains to respond to the presentation of novel stimuli. The WKYN rats made a significantly higher number of pretest avoidance responses and achieved a higher level of avoidance performance than SHR rats. In addition, during the pretest, WKYN rats were more active and had a shorter 1st trial latency. In Experiment II, the pretest phase was replicated with a manipulation of the intensity of the auditory cue. Although the WKYN rats had a higher rate of pretest avoidance than SHR rats, the rate of pretest avoidances increased with intensity in both strains. The WKYN rats had a shorter 1st trial latency and a shorter median latency for the 10 trials and were more active that SHR rats during the pretest. These results relate to age-independent behavioral characteristics of these strains and the question of reactivity to environmental stimulation.

Two-way shuttle box and lever-press avoidance in the spontaneously hypertensive and normotensive rat.

These experiments characterized behaviorally two strains of rat that have been selectively bred for blood pressure differences. Avoidance performances of the spontaneously hypertensive rat (SHR) and normotensive rat (WKYN) were examined under two conditions: a discrete-trial two-way shuttle box avoidance procedure and a discrete-trial lever-press avoidance procedure. The WKYN strain reached a higher level of acquisition in the two-way shuttle box task than the SHR strain, but this difference was confounded by an initial difference in pretest avoidance rate. In contrast, the SHR strain was superior in the lever-press avoidance procedure under all conditions employed. These data are interpreted as being consistent with a hypothesis offered by Satinder that strains selectively bred for some behavioral feature may also differ in central arousal which will interact with task difficulty to determine performance differences. The data clearly indicate that the selective breeding for high and low blood pressure has simultaneously influenced the behavioral properties of these two strains.

The effects of overtraining on mediational processes in elderly males.

To examine the effects of overtraining on mediational processes, 81 male residents (aged 55 or above) of a VA domicillary were tested using a two-choice discrimination task. Upon reaching criterion, the men were given, 0, 15, or 30 overtraining trials and then shifted to either a reversal, intradimensional, or extradimensional task. Analysis of the error scores resulted in a significant initial versus shift task main effect and type of shift by initial versus shift task interaction. Further analysis indicated no difference among the three shift groups for the initial task. However, in the shift task, the reversal group had significantly fewer errors than the other two groups who were not statistically different. Participants thus appeared to be mediationally sufficient when reversal and extradimensional tasks were compared, but mediationally deficient when intra- and extradimensional, and reversal and intradimensional tasks were contrasted. While overtraining had no significant effect, examination of the three way interaction suggested potentially facilitative effects of overtraining and a possible regression effect among participants not receiving overtraining.

Positive and negative behavioral contrast in the rat.

Three groups of rats received either 8, 23, or 53 sessions of multiple variable-interval variable-interval baseline training before being shifted to a multiple extinction variable-interval schedule. The rate of responding during the unaltered component was higher for the groups shifted to multiple extinction variable-interval than for control groups remaining on multiple variable-interval variable-interval (positive contrast). Furthermore, when the multiple variable-interval variable-interval schedule was re-instated, stable negative contrast was found in the groups that had received 23 or 53 baseline sessions, but not for the group that had received only eight sessions. Positive and negative contrast were also demonstrated in the eight and 23-session groups when the multiple extinction variable-interval and multiple variable-interval variable-interval schedules were re-administered in further phases of the experiment. These results suggest that both positive and negative behavioral contrast can be obtained reliably in a species other than the pigeon.